\part Miscellaneous\\Constructions\endpart




\chapter Literal mode\endchapter

The basic mechanism for literal mode is really not all that complicated.
However, the final \lamstex\ definitions are complicated indeed, because
of
\bullist
\item special features that we want  to incorporate;
\item subtle possibilities for bugs;
\item the desire for generality.
\endbullist


In order to temporarily eliminate the third complicating factor, we will
first consider what is needed to define the particular version of literal 
mode in which *"1* is the delimiter and *""* is used to serve as the
escape character in literal mode.


\section{In-line literal mode\label{ILLM}}
The basic idea of in-line literal mode, with *"1* as the delimiter
and *""* as the  escape character, is to
**
\def\lit"1{\begingroup\litcodes@\litdefs@\tt\lit@}
"slip
\def\lit@#1"1{#1\endgroup}
**
where *\litdefs@* is the abbreviation
**
"hskip-50pt\def\litdefs@{\let\0=\empty\def\1{\char42 }\def\ {\char32 }\def\""{\char34 }}
**
and
*\litcodes@* changes all the category codes,
**
\def\litcodes@{\catcode`\\=12 
 \catcode`\{=12 \catcode`\}=12
 \catcode`\$=12 \catcode`\&=12 
 \catcode`\#=12 
 \catcode`\^=12 \catcode`\_=12
 \catcode`\@=12 \catcode`\~=12 
 \catcode`\%=12 \catcode`\""=0 }
**
so that these new category codes are in force before *\lit@* reads in its
argument.


The first line of this definition
says that *\* will be an ordinary character once
*\litcodes@* appears.
 The next two lines make
ordinary characters out of the characters with category codes ~*1*, *2*, *3*
and~ *4*. Category~*5* (end of line) isn't changed for in-line-literal mode,
so the next line just handles the character *#* with category code  ~*6*, and
the next line handles category codes~*7* and~*8*. We don't bother with
category~*9* (ignored character) and category~*10*~ (space)
will be attended to in a
moment. Categories~*11* and ~*12* (letter and other character) need no
special treatment. The next line handles category~*13* (active); the final
line handles category ~*14* (comment character), leaving
 category~*15* (invalid)
 alone, and then finally makes *""* the escape character.

Then *\lit"1..."1* will print out `*...*', with each of  the
tokens *\*, *{*, *}*, *$*, *&*, *#*, *^*, *_*, 
*@*, *~*, *%* being printed in the *\tt* font.
Moreover, within the *\lit"1..."1* region, *""0* will stand for *\empty*,
*""1* will stand for character~*42* on the *\tt* font, which is 
the *"1* symbol,  `*"" *' will stand for
character~*32*, which is the *" * symbol, and
*""""* will stand for character~*34* on the *\tt* font,
which is the *""* symbol.
 
 However, we also
want spaces to act specially.
*plain* \tex's
*\obeyspaces*  makes spaces active, and defines each active space to
give one space in the output.
 But we will want a different definition for literal mode.
If we first use
**
{\obeyspaces
\gdef\defspace@{\def {\hskip.5emminus.15em}}} 
**
so that *\defspace@* makes the active space give spacing suitable for
literal mode,  
then we can simply add 
**
\obeyspaces\defspace@
**
to the end of the definition of
*\litcodes@*.

Actually, we will use
**
{\obeyspaces
\gdef\defspace@{\def {\allowbreak\hskip.5emminus.15em}}}
**
Then a line break can occur between
spaces.  For example, \hbox{*\lit"1A    B"1*},
with four\vadjust{\nobreak}
 spaces between the letters, could  split after the second,
giving
`*A  *\null\linebreak
*B*'; two spaces remain at the end of the first line, although all
subsequent spaces  disappear before the second letter.
Note that *\allowbreak* is not only shorter than *\penalty0*, but much
preferable in this case, since we cannot afford to leave a space after
the~*0*, so would have to add *\relax* to be on the safe side.

\small  I made this choice so
that  the first line could at least indicate that more than one space was
involved, but it looked  too weird  to have spaces at the beginning of 
the next line.  If that more literal sort of literal mode is preferred,
it  is only necessary  to define the  active space to mean
**
\allowbreak\hbox to.5em{}\hskip0emminus.15em
**
In practice, one would presumably be printing *" *'s if the number of spaces
needs to be emphasized.	
\endsmall



The *\allowbreak* at the beginning of the definition of
a space  in literal mode does introduce one slight complication: we should
**
\def\lit"1{\leavevmode\begingroup . . .}
**
---otherwise a  `*\lit"1 *' at  the beginning  of a paragraph will 
contribute an *\allowbreak* in {\it vertical\/}  mode, possibly overruling
a *\nobreak* that occurs before  it.


Moreover, the definition of *\lit@* should be changed to
**
\def\lit@#1"1{#1\endgroup\null}
**
so that a *\lit"1..."1* construction ending with a space won't have this
space deleted by any succeeding *\unskip*. \pagelabel{LITN}

Making spaces active means that we don't have to say *\frenchspacing*,
since now there aren't any spaces after punctuation. However, as {\it The
\tex book\/} points out (page~381), there's another slight problem, because
the *\tt* font has the ligatures *?"0`* and *!"0`*, which print
as {\tt?`} and {\tt!`} respectively (sigh). So we 
must
**
{\catcode`\`=\active\gdef`{\relax\lq}}
**
and then use
**
\catcode`\`=\active\obeyspaces\defspace@
**
at the end of the
definition of *\litcodes@*.

Finally, we want to set the *\hyphenchar* of the *\tentt* font
(selected by *\tt*) to ~*-1*, so that hyphenation won't be allowed:
**
\def\lit"1{\leavevmode\begingroup\litcodes@\litdefs@
 \tt\hyphenchar\tentt=-1 \lit@}
**



\small
If the possibility of hyphenation is preferred, this last clause
can simply be omitted.
Or one could add
**
\def\-{\discretionary{\char45 }{}{}}
**
to the *\litdefs@*, so that *""-* could be used for a discretionary hyphen.

\andsmall 
 In the \lamstex~Manual, *\tt* means *\tentt*
for  the usual 10~point text, but  *\ninett* in 9~point type (used for
these ``small  print'' sections), and *\eighttt* in 8~point (used for the
footnotes). The style file for the manual simply sets the
*\hyphenchar*   of  all three to ~*-1* at  the beginning,  but
a more complicated scheme could be used.
For example, we could have 
*\tenpoint* define *\pointsize@* to be~*t*, and *\ninepoint* define
*\pointsize@* to be~*n*, and *\eightpoint* define
*\pointsize@* to be ~*e*. And then we could replace the clause
**
\hyphenchar\tentt=-1
**
with
**
\if\pointsize@ t\hyphenchar\tentt=-1 \else
 \if\pointsize@ n\hyphenchar\ninett=-1 \else
  \hyphenchar\eighttt=-1 \fi\fi
**

(As a matter of fact, the style file for the Manual does make use of
 *\pointsize@*,
 for defining the \lamstex\ logo, since the $\Cal A$, $\Cal M$,  and
$\Cal S$ need to be selected from different fonts for   different sizes.)
\endsmall


\section{Displayed literal mode}
For ``displayed'' literal mode, we are going to use *\obeylines* to
make *^^M* active, but we
will need a new definition of the active *^^M*.  It will be convenient 
to use
**
{\obeylines\gdef\letM@{\let^^M=\CtrlM@}}
**
where *\CtrlM@* will be defined in a moment, so that 
 *\letM@* will make *^^M* have the meaning  of  *\CtrlM@* once
*\obeylines*
has  appeared.

We can begin defining *\Lit"1* by:
**
\def\Lit"1{\bigskip\begingroup
 \litcodes@\obeylines\letM@\tt\Lit@}
**
We don't need to disable hyphenation, since we are going to be setting
each line  as a separate *\hbox* (and therefore the shrink in the
definition of the active space will also be  irrelevant). For reasons 
to be discussed in section~\Sref{WARY}, *\litdefs@* hasn't been included yet.

*\Lit@* will begin setting an *\hbox*, so we first declare
**
\newbox\litbox@
**
and then
**
\def\Lit@{\setbox\litbox@=\hbox\bgroup\litdefs@}
**
 
Thus, the *\Lit@* will  start setting *\box\litbox@* to be  whatever  
is on the current line, with the literal codes in effect, as well as
the temporary definitions from *\litdefs@*.
  When  we get  to the end  of the line, we will
encounter 
a *^^M*, which will have the meaning of *\CtrlM@*,  which  we can
define by
**
\def\CtrlM@{\egroup  "8CTRLM"8
 \box\litbox@
 \Lit@}
**
so that the *^^M*  will simply cause the *\hbox* containing  the line
to be added to the   vertical  list, and then start setting another
*\box\litbox@*.

In order to have the closing *"1* end the literal display, the simplest
method
is to make the *"1* {\it active\/} during the display and have it defined by
**
\def"1{\egroup\endgroup\bigskip}  "8DEFSTAR3"8
**
The *\egroup* ends the *\box\litbox@*
 that started being set at the beginning of
the line containing the *"1*, but instead of adding this (presumably
empty) box to the vertical list, we simply supply the *\endgroup* that
matches the *\begingroup* contributed by *\Lit"1*.

In order to do this, we need to do something like
**
{\catcode`\"1=\active
 \gdef\defstar@{\def"1{\egroup\endgroup\bigskip}}  "8defstar"8
}
**
so that *\defstar@* will define *"1* properly once it is active, and then
**
\def\Lit"1{\bigskip\begingroup
 \litcodes@
 \catcode`\"1=\active\defstar@
 \obeylines\letM@\tt\Lit@}
**


The only slight problem with our definition  is that  the very first line
of a 
**
\Lit"1
 . . .
 . . .
"1
**
contributes an empty box. To take care of this, and for later purposes
(sections~\Sref{PPB} and ~\Sref{LPB}), we will declare a counter
**
\newcount\litlines@
**
which *\Lit"1* will set to~*0*, and then we will have
*\CtrlM@* (page~\ref{CTRLM}) simply increase *\litlines@* by~*1* if it
is~*0*, but add *\box\litbox@* if *\litlines@* is not~*0*.\pagelabel{LCNT}

\section{Notes for the wary\label{WARY}}
Although we still have many features to add, 
there are already some important point to be made
 about our definitions.  

First of all,
*\Lit"1* ends up processing only one line at a time.  Consequently,
there is no limit on the number of lines before the ending *"1*.

Second, we were careful to arrange that *\litdefs@*
will be in force only within each individual *\box\litbox@*.

 {\bfit And this is
extremely important:\/} After any particular *\box\litbox@* has been placed on
the main vertical list, \tex\ may decide to exercise the *\output* routine,
possibly long before the *\endgroup* supplied by the final *"1*.
If we had put *\litdefs@* right into the definition of
*\Lit"1*, then *\litdefs@* would be in effect when the
*\output* routine is invoked,
which could lead to havoc.  For example, suppose that in the book style
we have typed
**
\chapter The \LamSTeX\ Co\""op\endchapter 
**
so that even-numbered pages will use 
**
The \LamSTeX\ Co\""op
**
in the running heads. Then if this running head happened to be
 typeset while the literal
mode definitions are in force, we would end up with
\medskip
\centerline{\cmtenrm \def\LamSTeX{L\kern-.4em\raise.3ex
 \hbox{$\ssize\Cal A$}\kern-.25em
 \lower.4ex\hbox{\eightsy M}\kern-.1em{$\Cal S$}-\TeX}
The \lamstex\char32 Co\char34 op}
\medskip
\noindent since the `{\cmtenrm\char32 }' symbol is
*\char32* in the Computer Modern fonts, while *\char34* is
{\cmtenrm\char34 }.
Similarly, the user should be able to define *\0* and *\1*,
and have them used in running heads, without worrying about them
changing definitions if the output routine is invoked in the middle of
literal mode.


\section{Prohibiting page breaks\label{PPB}}
Normally, we want to prohibit breaks between  lines of displayed literal
material, so we also want to add a penalty after *\box\litbox@*.
We will declare a new  counter
**
\newcount\interlitpenalty@
\interlitpenalty@=10000
**
and we will have *\CtrlM@*  (page~\ref{CTRLM})
add *\penalty\interlitpenalty@*  before the current
*\box\litbox@* except for the very first box
(other
constructions, see section~\Sref{LPB}, can insert other penalties, or
give different values to *\interlitpenalty@*). 
  The following definition
takes care of this, together with the fact that we also
don't want the empty box
from the first line  (page~\ref{LCNT}):
**
\def\CtrlM@{\egroup
 \ifcase\litlines@ 
  \advance\litlines@ by 1 
 \or
  \box\litbox@ \advance\litlines@ by 1
 \else
  \penalty\interlitpenalty@\box\litbox@
 \fi
 \Lit@
**
Notice that with this arrangement,
 *\penalty\litpenalty@* ends up being added after each *\box\litbox@*,
{\it except\/}
the last box,\pagelabel{nolastpen}
 so that a page break can occur at the *\bigskip* supplied by
the closing *"1* (page~\ref{DEFSTAR3}); an explicit *\penalty* could be added
before the *\bigskip* if we wanted to discourage or encourage a page
break at that point.


\section{Indentation}
We usually want 
displayed literal  constructions to be indented by a  certain amount. So
we declare a new dimension
**
\newdimen\litindent
**
with the default value
**
\litindent=20pt
**
and we add *\hskip\litindent* at the beginning of each box:
**
\def\Lit@{\setbox\litbox@=\hbox\bgroup\litdefs@\hskip\litindent} 
**


\section{{\ninerm TAB}'s}Proper interpretation of the {\ninerm TAB}
character (*^^I*)
 is another
feature that we want to add.
We will use
**
{\catcode`\^^I=\active\gdef\letTAB@{\let^^I=\TAB@}}
**
so that *\letTAB@*  will make an active *^^I* mean *\TAB@*, which we
will define in a moment, and then we will add
**
\catcode`\^^I=\active\letTAB@
**
to the definition of *\Lit"1*, before the *\obeylines*.

For *\TAB@*, we want,
first of all, to allow for variances in the spacing for {\ninerm TAB}'s.
So
we will create a new counter,  with the default value ~*8*,
**
\newcount\littab@
\littab@=8
**
as well as the construction *\littab*, to change the value,
**
\def\littab#1{\littab@=#1\relax}
**

Every time that we encounter a *^^I* while we
*\setbox\litbox@*, we want to supply an *\egroup*, so that *\box\litbox@*
will be complete, add extra space at the end of
 *\box\litbox@* so that it has the requisite
width (namely the next multiple of *\littab@*
times the width of *\hbox{\tt0}*), and then include all this at the beginning
of another 
**
\setbox\litbox@=\hbox\bgroup\litdefs@
**
 {\it The~ \tex book}, page~391, gives
a simple way to find the required extra space:
 If *\dimen@* is the width of our box,
and *\dimen@ii* is *\littab@* times the width of *\hbox{\tt0}*, then
 to see how many times 
*\dimen@* fits within  *\dimen@ii*, we can simply
**
\divide\dimen@ii by \dimen@
\multiply\dimen@ii by \dimen@
**
Here *\dimen@* will be converted to its equivalent in scaled points (i.e.,
*1pt* will become~*65536*). At the end, *\dimen@ii* will be the largest
multiple of *\dimen@* that is 
 $\le$ ~*\dimen@ii*, 
so we will just have to increase *\dimen@* by *\littab@* times the
width of *\hbox{\tt0}* to move to the next tab.
\footnote{Although \tex\ indicates dimensions with decimal points, internally
all dimensions are expressed in terms of scaled points. Consequently, these
calculations will not have any rounding errors.}
 We have to remember,
however, that all our boxes begin with an extra *\litindent* amount of
space: 
**
\def\TAB@{\egroup
 \dimen@=\wd\litbox@
 \advance\dimen@ by -\litindent
"2
 \setbox0=\hbox{\tt0}%
"2
 \dimen@ii=\littab@\wd0
 \divide\dimen@ by \dimen@ii
 \multiply\dimen@ by \dimen@ii
"2
 \advance\dimen@ by \littab@\wd0
 \advance\dimen@ by \litindent
 \setbox\litbox@=\hbox\bgroup\litdefs@\hbox to\dimen@
  {\unhbox\litbox@\hfil}}
**

\section{Widow control\label{WC}}
In order to provide control over widow lines before literal
displays, we will make
 literal displays behave very much like displayed formulas.
We first use
**
\def\Lit"1{\ifhmode
 $$\abovedisplayskip=\bigskipamount
 \abovedisplayshortskip=\bigskipamount
 \belowdisplayskip=0pt \belowdisplayshortskip=0pt
 \postdisplaypenalty=10000
 $$\vskip-\baselineskip\else\bigskip\fi
 \begingroup . . . 
**
to produce an empty displayed formula right above the displayed literal
mode
material. The settings for *\abovedisplayskip* and for
the `*short*' version ensure that a *\bigskip* will precede this
formula. The settings for *\belowdisplay* and for the `*short*' version
ensure that there is no extra space between this empty displayed formula
and the displayed literal mode material. The
*\vskip-\baselinekip* deletes the extra space that this empty
formula contributes.
Finally, the empty display and the display   
literal mode material are kept
on the same page by the *\postdisplaypenalty*.

   Consequently,
\tex's page breaking decisions before *\Lit"1* material, will be the
same as before displayed formulas.

If we are already in vertical mode, we just add the *\bigskip* (we don't
want to add an empty formula in that case, since *$$...$$* in vertical
mode actually produces an extra blank line [{\it The \tex book}, page~316]).

\small As mentioned on page~85 of the \lamstex~Manual, changing the values of
*\abovedisplayskip*, etc., in this definition will change the amount of
space before a literal display. One could even add a clause
**
\predisplaypenalty=...
**
changing *\predisplaypenalty* from its default value of ~*10000*,
 to allow, or encourage, page breaks before a literal display
(if this done, then
a *\penalty* of that amount should be added before the *\bigskip* in the
*\else* clause above).
 However, the last line
on page~85 is just wrong: changing *\displaywidowpenalty* within the formula
won't affect anything.
\endsmall


As with displayed formulas (compare section~\Sref{pretend1}),
special care is required in the
definition of *"1* made by *\defstar@* (page~\ref{DEFSTAR3}), in case
an invisible construction follows. Basically we need to augment
the definition to
**
\egroup\endgroup\bigskip
\vskip-\parskip
\noindent@@\futurelet\next\pretendspace@
**
to start a *\noindent*'ed paragraph, and take care of the fact that
an invisible construction may follow (compare
page~\ref{ADDFNP}). But now we have an extra complication: we must 
skip over the space following the *"1* before adding the *\noindent@@*, so
that our *\noindent*'ed paragraph doesn't begin with an extra space.
So we really need
**
\egroup\endgroup\bigskip
\vskip-\parskip
\def\next@{\noindent@@\futurelet\next\pretendspace@}
\FNSS@\next@
**

\small! As in the case of a displayed formula (page~\ref{WARNPAR}),
users must be warned against adding ``invisible'' constructions
at the end of a literal display that ends a paragraph.

\andsmall The treatment of the end of display literal mode has been changed
from version~*1* of \lamstex@, where a displayed formula was added at the end
also (with undesirable side effects).
\endsmall


\section{Page breaks\label{LPB}}
Within a literal display we want *\displaybreak* to force a page break
when it appears on a line by itself; similarly *\allowdisplaybreak* should
allow a page break, and *\allowdisplaybreaks* should allow a page break
at that line and all succeeding lines.


Within the definition of *\Lit"1* we will add
**
\def\displaybreak{\egroup\break\litlines@=0 \Lit@}
**
The first *\egroup* ends the *\box\litbox@* that
 was being set at the beginning
of the line containing the 
**
""displaybreak
**
The *^^M* at the end of this line is still there, and will end an empty
*\box\litbox@* started by the *\Lit@*. Since we have set *\litlines@=0*,
however, this box will not appear on the vertical list, nor will a penalty
appear before the next *\box\litbox@*.

Thus,
\setbox0\hbox{\<a line of the literal display\>}%
\setbox1\hbox{\<the next line of the literal display\>}%
**
"box0
""displaybreak
"box1
** 
will produce
\setbox0\hbox{\<a line of the literal display\>}
\setbox1\hbox{*\null* box} 
\setbox6\hbox{*\vskip -\baselineskip               *} % 15 spaces
\setbox1\hbox to \wd6{\unhbox1 \hfil}
\setbox2\hbox{empty box created by *\Lit@*}
\setbox3\hbox{appropriate *\baselineskip* glue for next box}
\setbox4\hbox{put in by the definition}
\setbox5\hbox{\<the next line of the literal display\>}
**
"box0
\penalty -10000 
"box3 
"box5
** 
The
appropriate *\baselineskip* glue will disappear
after the page break at the *\penalty-10000*, 
so the next page will  start with the second line
(preceded by suitable *\topskip* glue).
 
\medbreak

Similarly, we will define 
**
\def\allowdisplaybreak{\egroup\allowbreak\litlines@=0 \Lit@}
**
Then
\setbox0\hbox{\<a line of the literal display\>}
\setbox1\hbox{\<the next line of the literal display\>}
**
"box0
""allowdisplaybreak
"box1
**
will produce
\setbox0\hbox{\<a line of the literal display\>}
\setbox1\hbox{*\null* box}
\setbox6\hbox{*\vskip -\baselineskip               *} % 15 spaces
\setbox1\hbox to \wd6{\unhbox1 \hfil}
\setbox2\hbox{empty box created by *\Lit@*}
\setbox3\hbox{appropriate *\baselineskip* glue for next box}
\setbox4\hbox{put in by the definition} 
\setbox5\hbox{\<the next line of the literal display\>}
**
"box0
\penalty 0
"box3
"box5
**

Finally, we will define
**
\def\allowdisplaybreaks{\egroup\allowbreak
 \interlitpenalty=0 \litlines@=0 \Lit@}
**
In this case, 
\setbox0\hbox{\<a line of the literal display\>}
\setbox1\hbox{\<the next line of the literal display\>}
**
"box0
""allowdisplaybreaks
"box1
**
produces
\setbox0\hbox{\<a line of the literal display\>}
\setbox1\hbox{*\null* box}
\setbox2\hbox{empty box created by *\Lit@*}
\setbox3\hbox{appropriate *\baselineskip* glue for next box}
\setbox4\hbox{put in by the definition} 
\setbox5\hbox{\<the next line of the literal display\>}
**
"box0
\penalty 0 
"box3
"box5
\penalty 0 
 . . .
**
with a *\penalty0* after all succeeding lines of the literal display,
 except the very last (see page~\ref{nolastpen}).


\small This manual contains numerous page references to material in
a literal display. But
 a *\pagelabel* right before or right
 after the literal display couldn't be counted upon to give the proper page
number, especially since many displays were allowed to
split across pages.  So the style file contains the definition
**
\def\8#1\8{\pagelabel{#1}}
**
Then on page~\ref{NameHLcounter} I could type
\litindent=-20pt
**
\rightadd@#2\to\overlonglist@
 \edef\next@{\global\let\csname\exstring@#2@C\endcsname
  =\expandafter\noexpand\csname HL@C#1\endcsname}\next@  ""8NameHLcounter""8
**
so that *\ref{NameHLcounter}* could be used on page~\ref{useNameHLcounter}
 to refer to the page containing
this line.\restorelitindent
\endsmall


\section{\CS{Litbox}\label{CSLITBOX}}For the construction
**
\Litbox#1="1
 . . .
"1
**
we can first use
**
{\catcode`\"1=\active
 \gdef\defboxstar@{\def"1{\egroup\egroup\endgroup}}
}
**
so that *\defboxstar@* defines *"1* once *"1* is active, in a
different manner than *\defstar@* did (adding an extra *\egroup*, and
omitting the remaining material).
Then we want a definition like
**
\def\Litbox#1="1{\begingroup\defboxstar@
 \litcodes@\tt\catcode`\^^I=\active\letTAB@
 \obeylines\letM@\global\setbox#1=\vbox\bgroup
 \litindent=0pt \litlines@=0 \Lit@}
**
The *\litindent=0pt* eliminates extra space at the beginning of each\linebreak
*\box\litbox@*. All these boxes are simply stacked inside the *\vbox*,
and then the closing *"1* supplies an *\egroup* to end the (empty)
*\box\litbox@* already begun, another *\egroup* to end the *\vbox*, and a
final *\endgroup* to match the *\begingroup*.

We might as well also add in
the definition of *\allowdisplaybreak* and
*\allowdisplaybreaks*,
 in case
the created box is later *\unvbox*'ed.

But there is a slight problem with our whole scheme,
 because we don't want the
 assignment *\setbox#1* to be global
when *#1* is even (section~\Sref{LANDG}).
  To get around
this, we will declare a new box
**
\newbox\Litbox@
**
and
*\global\setbox\Litbox@*, and then after the *\endgroup* supplied by the
concluding *"1* we will *\setbox#1\box\Litbox@* for even~*#1*, but
add a *\global* for odd~*#1*:
**
\def\Litbox#1="1{\begingroup
 \ifodd#1\relax\aftergroup\global\fi
 \aftergroup\setbox\aftergroup#1%
 \aftergroup\box\aftergroup\Litbox@
 \defboxstar@
 \litcodes@\tt\catcode`\^^I=\active\letTAB@
 \obeylines\letM@\global\setbox\Litbox@=\vbox\bgroup
 \litindent=0pt \litlines@=0 \Lit@}
**
The various *\aftergroup* tokens---*\global* (if *#1* is odd), 
*\setbox*, *#1*, *\box*, and 
*\Litbox@*---are
saved up and performed after the final *\egroup* provided by the final *"1*;
in other words,  *\setbox#1\box\Litbox@* is performed after *\box\Litbox@* has
been (*\global*'ly) set.


\section{The general definition}
Now that we have all the pieces, let's try to put them together, and
allow for greater generality.

We begin with things that don't depend on the particular choice of the
literal delimiter or backslash.

\C**
\newdimen\litindent
\litindent=20pt
\newbox\litbox@
\newbox\Litbox@
\newcount\interlitpenalty@
\interlitpenalty@=10000
\newcount\litlines@
"slip
{\obeyspaces\gdef\defspace@{%
 \def {\allowbreak\hskip.5emminus.15em\relax}}}
"slip
{\obeylines\gdef\letM@{\let^^M=\CtrlM@}}
"slip
{\catcode`\`=\active\gdef`{\relax\lq}}
"slip
\def\CtrlM@{\egroup
 \ifcase\litlines@ 
  \advance\litlines@ by 1 
 \or
  \box\litbox@ \advance\litlines@ by 1
 \else 
  \penalty\interlitpenalty@ \box\litbox@
 \fi
 \Lit@}
"slip
\def\Lit@{\setbox\litbox@=\hbox\bgroup\litdefs@
 \hskip\litindent}
"slip
\newcount\littab@
\littab@=8
\def\littab#1{\littab@=#1\relax}
"slip
{\catcode`\^^I=\active\gdef\letTAB@{\let^^I=\TAB@}}
"slip
\def\TAB@{\egroup
 \dimen@=\wd\litbox@
 \advance\dimen@ by -\litindent
 \setbox0=\hbox{\tt0}%
 \dimen@ii=\littab@\wd0
 \divide\dimen@ by \dimen@ii
 \multiply\dimen@ by \dimen@ii
 \advance\dimen@ by \littab@\wd0
 \advance\dimen@ by \litindent
 \setbox\litbox@=\hbox\bgroup\litdefs@
  \hbox to\dimen@{\unhbox\litbox@\hfil}}
**

We want to
allow the possibility that no literal backslash has been chosen. For this
purpose, we will first
**
\let\litbs@=\relax
**
and then have *\litdelimiter#1* redefine *\litbs@*, so that we can
insert *\litbs@* within our definitions whether or not a literal backslash
has been chosen.

*\litdelimiter#1* 
must define *\litbs@* so that it 
first sets the category code of *#1* to ~*0*
For this we can use
**
\edef\litbs@{\catcode`\string#1=0  ...
**
In this *\edef*, the only thing that gets expanded is the *\string#1*. Since
this gives us a character *C* of type~*12*,
**
\catcode`C=0
** 
without the usual *\* after the *`* is quite legitimate; that's fortunate,
since
**
\catcode`\#1=0
**
would be totally misinterpreted as
\setbox0\hbox{(*35* is the category code of *#*)}
**
\catcode 351=0     "box0
**

\pagebreak

When we say *\litdelimiter""* we also want *\litbs@* to save away the
definition
**
\def\""{\char`\string""}
**
in *\litbs@@*,
and similarly for any other
argument that may be 
used with\linebreak *\litdelimiter*. Here we will need our
old *\expandafter\noexpand* trick (pages~\ref{EXNE} and~\ref{EXNE2}):
\C**
\let\litbs@=\relax
\let\litbs@@=\relax
"slip
\def\litbackslash#1{%
 \edef\litbs@{%
  \catcode`\string#1=0
  \def\noexpand\litbs@@{\def\expandafter\noexpand
   \csname\string#1\endcsname{\char`\string#1}}}%
 }%
**

*\litcodes* can now be defined by
\C**
\def\litcodes@{\catcode`\\=12 
 \catcode`\{=12 \catcode`\}=12
 \catcode`\$=12 \catcode`\&=12 
 \catcode`\#=12 
 \catcode`\^=12 \catcode`\_=12
 \catcode`\@=12 \catcode`\~=12 \catcode`\""=12 
 \catcode`\;=12 \catcode`\:=12 
 \catcode`\!=12 \catcode`\?=12
 \catcode`\%=12 
 \litbs@\catcode`\`=\active\obeyspaces\defspace@}
**
Notice that we need the *\catcode`\""=12* since *""* is normally active in
\lamstex@. The *\litbs@* is placed after all the other *\catcode*'s, since
it may effect a further category code change (e.g., the category
code of *""* may then be changed to~*0*).

\pagebreak

The extra *\catcode*'s for *;* and *:* and *!* and *?* are inserted 
just in case any of these have been made active for French styles (compare
~\Sref{ALF}).

\medskip

Now comes a tricky part. *\litdelimiter#1* will define *\Lit#1*, and 
part of this definition will be to make *#1* active and then properly
define it.  So we want a construction, *\activate@#1*, which will
define *#1* properly when it is active. But putting
**
\def#1{...}
**
in our definition won't work, since the *#1* will be read in before *#1*
actually is active!  So we will resort to the *\lowercase* trick. We first
use
**
\lccode`\~=`#1
**
to make the *\lccode* of the {\it active\/} character~ *~* be~ *#1* (only an
ordinary character is allowed for the literal delimiter, so the *`#1* is
fine). This means that when ~*~* appears within a *\lowercase* it will be
turned into an {\it active\/}~*#1*.

So then we can do something like
**
\lowercase{%
 \gdef\defdelimiter@{\def~{...}}
}
**
so that *\defdelimiter@* will define our delimiter~ *#1* properly once it is
active. We will need a similar, but different,
 definition for the redefinition of~*#1* for
*\Litbox*, so we will let *\activate@* have two arguments---the first,
which will always be either *0* or *1*, determining which value the
global scratch token *\Next@* (see page~\ref{GNXT})
will be given:
\C**
\def\activate@#1#2{{\lccode`\~=`#2% 
 \lowercase{%
"2
  \if0#1%
"2
   \gdef\Next@{\def~{\egroup\endgroup
    \bigskip\vskip-\parskip
"2
    \def\next@{\noindent@@\futurelet\next\pretendspace@}%
     \FNSS@\next@}}%
"2
  \else 
   \gdef\Next@{\def~{\egroup\egroup\endgroup}}%
  \fi
  }% 
}}
**

Another thing *\litdelimiter#1* will do is to set *\litdelim@* to be
the character code for ~*#1*:
**
\edef\litdelim@{\char`#1}
**
since this will be used by *\litdefs@*:
\C**
\def\litdefs@{\let\0=\empty\def\1{\litdelim@}%
 \def\ {\char32 }\litbs@@}
**
Remember that *\litbs@@* is either *\relax* or the proper definition of *\""*
if *\litdelimiter""* has been used, etc.

Finally, *\litdelimiter#1* then defines *\lit#1*, *\Lit#1* and
the construction
*\Litbox##1=#1*.
The definitions are just those in the previous sections, except that
*\Lit#1* will use
**
\catcode`#1=\active \activate@0#1\Next@
**
to get the literal delimiter ~*#1* active, and give it the proper definition,
while *\Litbox##1=#1* will use
**
\catcode`#1=\active \activate@1#1\Next@
** 
to get the proper definition for that case:
\C**
\def\litdelimiter#1{%
 \edef\litdelim@{\char`#1}%
"2
 \def\lit#1{\leavevmode\begingroup\litcodes@\litdefs@
  \tt\hyphenchar\tentt=-1 \lit@}%
 \def\lit@##1#1{##1\endgroup\null}%
"2
 \def\Lit#1{\ifhmode$$abovedisplayskip=\bigskipamount
  \abovedisplayshortskip=\bigskipamount
  \belowdisplayskip=0pt \belowdisplayshortskip=0pt
  \postdisplaypenalty=1000
  $$\vskip-\baselineskip\else\bigskip\fi
"2
  \begingroup\litlines@=0
  \catcode`#1=\active \activate@0#1\Next@
"2
  \def\displaybreak{\egroup\break\litlines@=0 \Lit@}%
"2
  \def\allowdisplaybreak{\egroup\allowbreak\litlines@=0 
   \Lit@}%
"2
  \def\allowdisplaybreaks{\egroup\allowbreak
   \interlitpenalty@=0 \litlines@=0 \Lit@}
"2
  \litcodes@\tt\catcode`\^^I=\active\letTAB@
  \obeylines\letM@\Lit@}%
"2
 \def\Litbox##1=#1{\begingroup
  \ifodd##1\relax\aftergroup\global\fi
  \aftegroup\setbox\aftergroup##1\aftergroup\box
   \aftergroup\Litbox@
  \def\allowdisplaybreak{\egroup\allowbreak
   \litlines@=0 \Lit@}%
"2
  \def\allowdisplaybreaks{\egroup\allowbreak
   \interlitpenalty@=0 \litlines@=0 \Lit@}%
  \catcode`#1=\active \activate@1#1\Next@
"2
  \litcodes@\tt\catcode`\^^I=\active\letTAB@
  \obeylines\letM@\global\setbox\Litbox@
  =\vbox\bgroup\litindent=0pt \litlines@=0 \Lit@}%
 }
**





\sectiong{Nicer syntax\label{NICERSYN}}
Long before I wrote literal mode for \lamstex@, I had
my own literal mode, based upon making *"1* permanently active, with
**
"1 ... "1
**
giving in-line literal mode, and
**
"1"1
 . . .
 . . .
"1"1
**
giving displayed literal mode. Thus, *"1* worked quite analogously to *$*,
except that it gave literal mode instead of math mode.

Based on the constructions of
the previous section, we might
implement this approach as follows:
\setbox0\hbox{\<previous definition for *\lit"1*\>}
\setbox1\hbox{\<previous definition for *\Lit"1*\>}
**
\catcode`\"1=\active
\def"1{\futurelet\next\star@} 
\def\star@{\ifx\next"1\expandafter\star@@\else
 \expandafter\star@@@\fi}
\def\star@@@{"copy0}
\def\star@@"1{"copy1}
**
except that *\star@@* should then (temporarily) redefine *"1* as
**
\def"1"1{\egroup\endgroup ... }
**

Actually, there is a subtle bug here:\pagelabel{SUBTLEBUG}
 The *\futurelet\next* causes
\tex\ to read the token after the *"1*, and since this has been done
{\it before\/} the *\litcodes@*, this next token will have the wrong
category code permanently imprinted on it.
Consequently, we have to start with
**
\catcode`\"1=\active
\def"1{\begingroup\litcodes@\futurelet\next\star@}
**
to get things right.


Also, the syntax for *\Litbox* should be changed correspondingly, to
\setbox0\hbox{\it n}
**
\Litbox"box0="1"1
 . . . 
"1"1
**



\medskip

I found this arrangement so much more pleasant than the *\lit* and *\Lit*
syntax (even after I had abbreviated *\lit* to *\l* and *\Lit* to
*\L*) than I have used it throughout this manual. 

\medskip

Making *"1* active does necessitate some small changes in other parts of
\lamstex@. First of all, I changed the *plain* definition of *\ast* to
**
\def\ast{\string"1}
**
so that *\ast* just gives the category~*12* *"1*, and can thus
be used both in text
and in math mode (giving the symbol \ast\ in text, but $\ast$ in math).

Then I had to examine all the places where *"1* already appears in
*lamstex.tex*.  
\list\item
Its appearance in the definition of *\fnsymbol* requires
no change, since the *"1* appearing there is a type~*12*~*"1*.
\item
However, the definition of *\starparts@* needs to be restated, after 
*"1* has been made active,
 because it uses a 
*"1* as part of the syntax for the subsidiary control sequence *\next@*.
\item
Similarly, the definition of *\starparts@@* uses *"1* as part of its syntax,
so it needs to be restated. 
\item
And the same was true of *\iabbrev*. Moreover, in this case,
 the *"1* in the replacement text
needs to be replaced with *\noexpand"1*.	
\endlist

There are also a few definitions for mathematics where *"1* appears.
\list\item
The first is in the definition of *\keybin@*
(section~\Sref{ALF}). Since *\ast* would now be used instead of *"1* in a
math formula, in the definition of *\keybin@*
the 
**
\ifx\next"1
**
clause needs to be replaced with
**
\ifx\next\ast
**
\item
It also appears in *\boldkey*. Although *\boldkey* is meant to be used
with symbols on the keyboard, rather than control sequences, it would probably
be reasonable to
change the clause
**
\ifx#1"1\mathcharii@203 \else
**
to 
**
\ifx#1\ast\mathcharii@203 \else
**
and agree that *\boldkey* can also be used with *\ast*.
\endlist

\medskip

\litindent=0pt

I would have loved to use this nicer syntax no matter what delimiter the user
chooses, but it seemed utterly hopeless to arrange this. Nevertheless, 
to encourage people, here
in its entirety is the additional code that makes
 *"1* and *""*  the
literal delimiter and escape character with this nicer syntax.  With almost
no modifications,
 it should function for other pairs, although one must then look
carefully through all the \lamstex\ macros to see what modifications may be
needed because of the fact that another character has been made active.
It is doubly easier than the code of the previous section,
 not only because
we are dealing with a specific choice of literal delimiter and backslash, but
also because the literal delimiter is active to begin with.  Nevertheless,
the subtle bug mentioned on page~\ref{SUBTLEBUG} introduces the possibility
for an even yet more subtle bug, so there is an additional detail that
is discussed at length starting on page~\ref{DISCUSSB}.


**
\catcode`\"1=\active

"2
\def\ast{\string"1} % can be used both in text and in math

"2
\def\iabbrev"1#1#2{\ifindexing@\toks@{#2}%
 \immediate\write\ndx@
 {\noexpand\abbrev\noexpand"1\noexpand#1{\the\toks@}}\fi}

"2
\def"1{\begingroup\litcodes@\futurelet\next\star@}

"2
\def\litcodes@{\catcode`\\=12 
 \catcode`\{=12 \catcode`\}=12
 \catcode`\$=12 \catcode`\&=12 
 \catcode`\#=12 
 \catcode`\^=12 \catcode`\_=12
 \catcode`\@=12 \catcode`\~=12 
 \catcode`\%=12 
 \catcode`\`=\active \catcode`\""=0 \obeyspaces\defspace@}

"2
\def\star@{\ifx\next"1\expandafter\star@@\else\expandafter\star@@@\fi}

"2
%%% Code for "1..."1

\def\star@@@{\leavevmode\litdefs@\tt\hyphenchar\tentt=-1 \star@@@@}%

"2
\def\star@@@@#1"1{#1\endgroup}

"2
\def\litdefs@{\let\0=\empty\def\1{\char42 }\def\""{\char34 }\def\ {\char32 }}

"2
%%% Code for "1"1 ... "1"1

\def\newstar@{\def"1"1{\egroup\endgroup
 \bigskip\vskip-\parskip
"2
 \def\next@{\noindent@@\futurelet\next\pretendspace@}%
  \FNSS@\next@}}

"2
\def\star@@"1{"9\endgroup"9\ifhmode$$\abovedisplayskip=\bigskipamount
 \abovedisplayshortskip=\bigskipamount
 \belowdisplayskip=0pt \belowdisplayshortskip=0pt
 \postdisplaypenalty=10000
 $$\vskip-\baselineskip\else\bigskip\fi
 "9\begingroup\litcodes@"9
 \litlines@=0
 \newstar@ 
 \def\displaybreak{\egroup\break\litlines@=0 \Lit@}%
 \def\allowdisplaybreak{\egroup\allowbreak\litlines@=0 \Lit@}%
 \def\allowdisplaybreaks{\egroup\allowbreak
  \interlitpenalty@=0 \litlines@=0 \Lit@}%
 \tt\catcode`\^^I=\active\letTAB@\obeylines\letM@\Lit@}

"2
\def\boxstar@{\def"1"1{\egroup\egroup\endgroup}}

"2
\def\Litbox#1="1"1{\begingroup
 \ifodd#1\relax\aftergroup\global\fi
 \aftergroup\setbox
 \aftergroup#1\aftergroup\box\aftergroup\Litbox@
 \boxstar@
 \def\allowdisplaybreak{\egroup\allowbreak\litlines@=0 \Lit@}%
 \def\allowdisplaybreaks{\egroup\allowbreak
  \interlitpenalty@=0 \litlines@=0 \Lit@}%
 \tt\litcodes@\catcode`\^^I=\active\letTAB@\obeylines\letM@%
 \global\setbox\Litbox@=\vbox\bgroup\litindent=0pt \litlines@=0 \Lit@}

\catcode`\@=\active
**

\newpage

\andsmall! 
The boxed \pagelabel{DISCUSSB}
additions to the definition of *\star@@* are needed because of
a strange \tex\ ``feature''.

Suppose we type
**
\hangafter-2 \hangindent=20pt
Here are several ... 
lines of text.
\vskip1in
Here are several ... 
lines of text.

Here are several ... 
lines of text.
**
Then the first paragraph, implicitly ended by the *\vskip1in*,
  will have hanging indentation of 20~points for the first two lines
(like these small print notes),
while the next two paragraphs will be treated normally.  But now suppose
we type
**
\hangafter-2 \hangindent=20pt
Here are several ... 
lines of text.
{\vskip1in}
Here are several ... 
lines of text.

Here are several ... 
lines of text.
**
Then the second paragraph will also having hanging indentation for the
first two lines!!
 Reason:
The *\vskip1in*, implicitly ending the first paragraph,
 causes \tex\ to restore *\hangafter* and
*\hangindent* to their default values,
as with  any other locally defined \tex\ parameters.
\footnote{{\it The \tex book}, page~103,
 states that ``\tex\ automatically restores
[the values of *\hangindent* and *\hangafter*] at the end of every paragraph,
and (by local definitions) whenever it enters internal vertical mode.  For
example, hanging indentation that might be present outside of a *\vbox*
construction won't occur inside that vbox, unless you ask for it inside.''
I would take that to mean that the restoration of values is done globally
at other times (i.e., when ending a paragraph), but apparently that is not
the case.}
  So, after the *}* that follows the
*\vskip1in*, the values of  *\hangafter* and
*\hangindent* {\it are still\/}~*-2* and ~*20pt*, respectively!!



\andsmall!
If our definition of *\star@@* didn't have the *\endgroup* before the
**
\ifhmode$$ . . . $$
\vskip-\baselineskip\else\bigskip\fi
**
then something like
**
\hangafter-2 \hangindent=20pt
Here are several ... 
lines of text.
"1"1
  . . .
"1"1
**
would entail  a *\vskip* within a group, and thus give rise to this problem:
text following the closing *"1"1*, which is really a new paragraph, would
continue to have the same hanging indentation.
Once we are safely past that *\vskip*, we reinsert the
**
\begingroup\litcodes@
**
that we initially had.

\andsmallsmall As if that weren't confusing enough, it has to be admitted that
this extra code really isn't needed, after all, because  *\newstar@* 
defines *"1"1* in terms of *\noindent@@*, so that the closing *"1"1* 
essentially contributes a
**
\endgroup
\bigskip\vskip-\parskip
\noindent@@
**
and thus essentially
**
\endgroup
\bigskip\vskip-\parskip
\par
\noindent@
**
Now the *\par* causes the values of *\hangafter* and *\hangindent* to be
restored to their default values, outside the group ended by the *\endgroup*
(but *\noindent@* alone doesn't end a paragraph---it merely starts an
unindented paragraph in vertical mode, and has no effect in horizontal mode).

  But there's obviously no point tempting
fate  by relying on *\noindent@@* always being used instead of *\noindent@*.

\endsmall

\restorelitindent

\chapterg Literal mode in heading levels\endchapterg
As  mentioned in Chapter~\ref{foot}, our definitions
allow literal mode to work within
*\footnote*'s.
It might seem that it should be just as easy to allow literal mode
constructions within heading levels, but here the situation is  much
more complex.

Remember that something like
**
\hl1{Extra \lit"1}"1 errors}
**
must not only typeset `Extra *}* errors', it must also send
**
Extra \lit"1}"1 errors
**
off to the *.toc* file, and it's not very clear how we are going to get
these tokens, with unbalanced braces, stored inside a control sequence!
\footnote{If we are willing to process the argument a
token at a time, appropriately changing category codes each time we hit
a *\lit* token, then it can be done (although we might have problems if the
user has substituted some other control sequence for *\lit*). But it wouldn't
be pleasant: since
we can't put individual, unbalanced, braces into a token list, each time we
hit a (non-literal-mode) *{* we would have to record this fact, and then
add the *{* back in
 when the matching *}* is discovered, i.e., we would practically
have to rewrite \tex's scanner in \tex\ macros.}
Moreover, a *\footnote*, no matter how formatted, usually involves an
*\insert\footins{...}*, so a style file designer who wants to change the
appearance of a *\footnote*  probably won't to have
to worry about the trickery involved in allowing category changes. But it
seems much less reasonable to commit heading levels to something like
**
\global\setbox1=\vbox{...}
**
since heading levels for other style files might have to be handled quite
differently. 


Of course, in the great majority of cases, even when literal mode is used,
it won't be needed in
header levels. And 
even when literal mode material does occur in header levels, usually only
small snatches are needed, which can be handled quite easily with special
definitions. For example, for this manual, where
 control sequences appear quite often in heading levels, I defined
**
\def\CS#1{{\tt\char'134 #1}}
**
so that the next section  could be typed as
**
\section{Literal mode in \CS{HL} and \CS{hl}}
**
With a few definitions for the backslash~ *\* and the curly braces
*{* and *}*, virtually any literal mode material can be included in
heading levels.

For this reason,
*lamstex.tex* does not directly
address the problem of literal mode in heading levels.
  However, there is a subsidiary file,
*lithl.tex*, which adds new definitions that allow literal mode to be
incorporated, albeit somewhat
indirectly, within heading levels.

\section{Literal mode in \CS{HL} and \CS{hl}}
If the file *lithl.tex* is *\input*,
 before a *\litdelimiter* and *\litbackslash*
are declared, then *\lit"1..."1* will generally
act as before, but two special extensions
will be introduced:
\list
\item On the one hand, we can type 
\setbox0\hbox{\it n\,}
**
\lit","box0"1..."1
**
for $\hbox{\it n}=\hbox{*0*}, \dots, \hbox{*9*}$. This will not typeset
*...* in literal mode, but simply store the corresponding literal mode
tokens in a special storage space, one for each of *0*, \dots, *9*.
\item On the other hand, the combination
\setbox0\hbox{\it n}
**
\lit","box0
**
(where the next symbol is {\it not\/} a *"1*) will simply give a copy of
whatever is stored in storage space {\it n}.
\endlist

So, for example, the current section could be typed as
**
\lit0"1\HL"1
\lit1"1\hl"1
\section{Literal mode in \lit0 and \lit1}
**


*lithl.tex*  creates new boxes
**
\expandafter\newbox\csname lit@0\endcsname
\expandafter\newbox\csname lit@1\endcsname
 . . .
**
for the storage locations, and makes
*\lit*  a control sequence with an argument,
**
\lit#1
**
If *"1* is going to be the literal delimiter, then when the argument
*#1* is *"1*
we use *\lit@@@*, which is essentially the old *\lit"1*, but if *#1*
is not *"1* (and thus presumably one of *0*, \dots, *9*), we set
**
\count@=#1
**
and then use
**
\futurelet\next\lit@@
**

The *\futurelet* is needed
 to see whether the next character is a *"1* or not.
If it isn't (so that we have something like `*\lit0 and*'), then
we simply use 
**
\unhcopy\csname lit@\number\count@\endcsname\null
**
(the *\null* is added for the same reason that is was added to the
original definition of *\lit@* [page~\ref{LITN}]).
But if we now have a *"1*, so that we are in the case
\setbox0\hbox{\,\it n\,}
**
\lit"box0"1..."1
**
we use the routine *\lit@@@@*.

We might define *\lit@@@@* by
**
\def\lit@@@@"1{\prevanish@\begingroup
 \litcodes@\litdefs@\lit@@@@@}
"slip
\def\lit@@@@@#1"1{\toks@={#1}
 \global\expandafter\setbox
  \csname lit@\number\count@\endcsname
  =\hbox{\tt\the\toks@}
 \endgroup\postvanish@}
**
with 
*\prevanish@* and *\postvanish@*  added to 
 make constructions like *\lit*\,{\it n\,}*"1..."1*
 invisible, just in case they get used in a paragraph.

With such definitions,
**
\lit0"1\HL"1
\lit1"1\hl"11
\section{Literal mode in \lit0 and \lit1}
**
will indeed produce the current section title.  On the other hand, if
we are making a *.toc* file, then this section will simply appear as
\Evaluate\chapter\edef\chap{\number\Value}
\Evaluate\section\edef\sec{\number\Value}
**
\section{"chap."sec}
 {Literal mode in \lit0 and \lit1}
**
so we will also want to have 
**
\lit0"1\HL"1
\lit1"1\hl"1
**
written to the *.toc* file first.

This might seem fairly straightforward (after all the trickery to which we've
become accustomed), 
**
\def\lit@@@@@#1"1{\toks@={#1}
 \iftoc@
  \edef\next@{\write\toc@{\noexpand\noexpand
   \noexpand\lit\number\count@"1\the\toks@"1}\next@
  \fi
 . . .
**
but, alas, it can fail in a subtle way.

  Suppose that we wanted a
heading like
\bigskip
\hbox to\hsize{\hfil{\bf1.\enspace}Comparing *\" * and *\space*\hfil}
\medskip
\noindent and therefore typed
**
\lit0"1\"" "1
\lit1"1\space"1
\HL1 Comparing \lit0 and \lit1\endHL
**
Then the first line would cause the  *.toc* file to contain
**
\lit0 "1\\ "1
**
Reason: When we have dutifully established *\litcodes@* and *\litdefs@* before
exercising *\lit@@@@@*,
the token list *\toks@* contains two tokens: the first token is a 
type~*12*~*\*, and the second token is `control-space', i.e., the control
sequence whose name is `\hbox{*"" *}' when
 *""* is the escape character, and `\hbox{*\ *}' when
*\* is the escape character, etc.  When \tex\ goes to print that control
sequence in the *.toc* file, it will simply print it as `\hbox{*\ *}'.
 To put it another way, the tokens `\hbox{*\\ *}' that get written
really consist of a
type~*12*~*\* followed by a type~*0*~*\* followed by a space, but once the
tokens are written, the category codes become irrelevant.

To get around this problem, we use the following byzantine strategy. After
using *\litcodes@* to change the category codes, we add
**
\catcode`\""=12
**
so that *""* is just an ordinary character.  Then *\toks@* will be just the
ones that we want to write
 to the *.toc* file.  The problem, of course, is that
they are no longer the tokens that we want to put
 in the *\hbox*: we really have
to read in the *"1..."1* material once again, this time {\it without\/}
making the special change for *""*.  Although we cannot get \tex\ to back~
up and read the argument again,
nevertheless we  can reread the argument, by first {\it writing\/} the
token list *\toks@* to a temporary file, and then reading it in again with
the proper codes!
**
\newwrite\tempwrite@
\newread\tempread@
"slip
\def\lit@@@@"1{\prevanish@\begingroup\litcodes@
 \catcode`\""=12 \lit@@@@@}
"slip
\def\lit@@@@@@#1"1{%
 \toks@={#1}%
"2
 \iftoc
  \edef\next@{\write\toc@{\noexpand\noexpand
   \noexpand\lit\number\count@"1\the\toks@"1}\next@
 \fi
"2
 \immediate\openout\tempwrite@=\jobname.tmp
 \immediate\write\tempwrite@{\the\toks@}
 \immediate\closeout\tempwrite@
"2
 \catcode`\""=0 \litdefs@
"2
 \immediate\openin\tempread@=\jobname.tmp
 \read\tempread@ to \next@
 \immediate\closein\tempread@
"2
 \global\expandafter
  \setbox\csname lit@\number\count@\endcsname
  =\hbox{\tt\next@}
"2
 \endgroup
 \postvanish@}
**

Unfortunately, that doesn't quite work either, because
there is no way that *\next@* can reflect the exact number of spaces that
occurred at the end of the *"1..."1* sequence that we wrote
 to *\tempwrite*, since
spaces at the end of a line are always stripped off by \tex\ as it reads.
So yet another fillip has to be added: We will always add a *"1*
at the end of the sequence (this *"1* can't occur within the sequence,
although *""1* can appear to indicate this character), and then
we will strip off the *"1* and everything following (presumably just
the space inserted by the *^^M* at the end of the line) from *\next@*:
**
\def\lit@@@@@#1"1{%
 \toks@={#1}%
 \iftoc
  \edef\next@{\write\toc@{\noexpand\noexpand
   \noexpand\lit\number\count@"1\the\toks@"1}\next@
 \fi
"2
 \immediate\openout\tempwrite@=\jobname.tmp
 \immediate\write\tempwrite@{\the\toks@"9"1"9}%
 \immediate\closeout\tempwrite@
"2
 \catcode`\""=0 \litdefs@
 \immediate\openin\tempread@=\jobname.tmp
 \read\tempread@ to \next@
 \immediate\closein\tempread@
"2
 "9\def\nextii@##1"1##2\nextii@{\def\next@{##1}}"9%
 "9\expandafter\nextii@\next@\nextii@"9
"2
"2
 \global\expandafter
  \setbox\csname lit@\number\count@\endcsname
  =\hbox{\tt\next@}
"2
 \endgroup
 \postvanish@}
**



\section{The general definitions\label{GENDEFS}}
The previous section indicated definitions to be used when *"1* is the
literal delimiter, and *""* is the literal backslash.  Now we will give the
code in general.

The file *lithl.tex* begins, like *lamstex.tex* itself, with
\CC**
\catcode`\@=11
**
As illustrated here,
we will always
use double horizontal lines for code that is in subsidiary files, rather
than in *lamstex.tex* itself.


Since we are going to use *\new...* constructions we then declare
(compare page~\ref{NEWALLOC})
\CC**
\let\alloc@=\alloc@@
**

First we declare new boxes, 
\CC**
\expandafter\newbox\csname lit@0\endcsname
 . . .
\expandafter\newbox\csname lit@9\endcsname
**
and the input and output streams for the *.tmp* file,
\CC**
\newwrite\tempwrite@
\newread\tempread@
**

Since we are going to be changing the category code of the literal backslash,
if it has been chosen, *\litbackslash* will have to store extra information
that allows us to do this. We declare a counter,  initially with value~*-1*,
\CC**
\newcount\litbackslashno@
\litbackslashno@=-1
**
and we change the definition of *\litbackslash#1* so that it sets
the value of\linebreak
*\litbackslashno@* to the character code of~*#1*:
\CC**
\def\litbackslash#1{%
 \edef\next@{\litbackslashno@=`\string#1}\next@
 \edef\litbs@{%
  \catcode`\string#1=0
  \def\noexpand\litbs@@{\def\expandafter\noexpand
   \csname\string#1\endcsname{\char`\string#1}}}}
**

Then we add the necessary definitions of *\lit@* et~al\. to the definition of
*\litdelimiter*, with the category code of character *\litbackslashno@*
changed back to~*0* if *\litbackslashno@* isn't~*-1* (if it is, we haven't
declared an escape character for literal mode, so we don't have to worry
about things like *\"" *): 
\CC**
\def\litdelimiter#1{%
 \edef\litdelim@{\char`#1}%
"2
 \def\lit##1{\ifx##1#1\let\next@=\lit@\else
  \count@=##1\relax\def\next@{\futurelet\next@\lit@@}\fi
  \next@}%
"2
 \def\lit@{\leavevmode\begingroup\litcodes@\litdefs@
  \tt\hyphenchar\tentt=-1 \lit@@@}%
"2
 \def\lit@@@##1#1{##1\endgroup\null}%
 \def\lit@@{\ifx\next#1\let\next@=\lit@@@@\else
  \def\next@{\unhcopy\csname lit@\number\count@\endcsname
   \null}\fi
  \next@}%
"2
 \def\lit@@@@#1{\prevanish@
  \begingroup\litcodes@\ifnum\litbackslashno@=-1 \else
  \catcode\litbackslashno@=12 \fi\lit@@@@@}%
"2
 \def\lit@@@@@##1#1{\toks@={##1}%
  \iftoc@
  \edef\next@{\write\toc@{\noexpand\noexpand
   \noexpand\lit\number\count@#1\the\toks@#1}}\next@
  \fi
"2
  \ifnum\litbackslashno@=-1 \def\next@{\the\toks@}\else
   \immediate\openout\tempwrite@=\jobname.tmp
   \immediate\write\tempwrite@{\the\toks@#1}%
   \immediate\closeout\tempwrite@
"2
   \catcode\litbackslashno@=0 \litdefs@
   \immediate\openin\tempread@=\jobname.tmp
   \read\tempread@ to\next@
   \immediate\closein\tempread@
"2
   \def\nextiii@####1#1####2\nextiii@{\def\next@{####1}}%
   \expandafter\nextiii@\next@\nextiii@
  \fi
"2
  \global\expandafter
   \setbox\csname lit@\number\count@\endcsname
   =\hbox{\tt\next@}%
  \endgroup\postvanish@}%
"2
 \def\Lit#1{$\ifhmode$\abovedisplayskip=\bigskipamount
  \abovedisplayshortskip=\bigskipamount
  \belowdisplayskip=0pt \belowdisplayshortskip=0pt
  \postdisplaypenalty=1000
  $$\vskip-\baselineskip\else\bigskip\fi
"2
  \begingroup\litlines@=0
  \catcode`#1=\active \activate@0#1\Next@
"2
  \def\displaybreak{\egroup\break\litlines@=0
   \Lit@}%
"2
  \def\allowdisplaybreak{\egroup\allowbreak
   \litlines@=0 \Lit@}%
"2
  \def\allowdisplaybreaks{\egroup\allowbreak
   \interlitpenalty@=0 \litlines@=0 \Lit@}
"2
  \litcodes@\tt\catcode`\^^I=\active\letTAB@
  \obeylines\letM@\Lit@}%
"2
 \def\Litbox##1=#1{\begingroup
  \ifodd##1\relax\aftergroup\global\fi
  \aftergroup\setbox
  \aftergroup##1\aftergroup\box\aftergroup\Litbox@
  \def\allowdisplaybreak{\egroup\allowbreak
   \litlines@=0 \Lit@}%
"2
  \def\allowdisplaybreaks{\egroup\allowbreak
   \interlitpenalty@=0 \litlines@=0 \Lit@}%
  \catcode`#1=\active \activate@1#1\Next@
"2
  \litcodes@\tt\catcode`\^^I=\active\letTAB@
  \obeylines\letM@\global\setbox\Litbox@=\vbox%
  \bgroup\litindent=0pt \litlines@=0 \Lit@}%
}
**
Finally, we reassign *\alloc@* its original definition from *plain* \tex@,
and make *@* active again:
\CC**
\def\alloc@#1#2#3#4#5{\global\advance\count1#1by\@ne
 \ch@ck#1#4#2\allocationnumber=\count1#1
 \global#3#5=\allocationnumber
 \wlog{\string#5=\string#2\the\allocationnumber}}
\catcode`\@=\active
**

\setbox0\hbox{\,\it n\,}
\small
If the alternate syntax of section~\Sref{NICERSYN} is used, something 
different would be needed. For example, we might create *\SL* and *\UL*
(store literal mode material and use literal mode material), so 
that *\SL"box0"1..."1*
stores the material in location {\it n}, while
\setbox0\hbox{\,\it n}%
*\UL"box0*
uses it. With a little work, we could even arrange for
\setbox0\hbox{\,\it n}%
*"1"box0..."1*
to work like *\SL*\,{\it n}*"1..."1*, so that only *\UL* would be needed.
(For the case of literal mode material that happened to begin with a digit,
like
*0...*,
we would then have to use
*"1""00..."1*
to print it.)
\endsmall




\chapter Title, author, etc., in the default style\endchapter
There is, happily, not much interesting about *\title*,
*\author*, *\affil*, and *\date* in the default style, except that,
for the sake of economy, we carefully arrange to avoid introducing any flags
to tell us which of these constructions have been used.


We allow the possibility of an empty title, so we declare
\C**
\newbox\titlebox@
\setbox\titlebox@=\vbox{}
*
and we
\C**
\righadd@\title\to\overlonglist@
**
since we want *\overlong\title* to work.  Then
*\title"allowbreak..."allowbreak\endtitle* will just set 
*\box\titlebox@*. This box won't actually be printed until the *\maketitle*
appears; the main purpose of this sort of arrangement is to allow 
*\title*,
*\author*, *\affil*, and *\date* to occur in any order before the
*\maketitle*, so that the user doesn't need to know in which order these
various elements have to be specified.

The  *\title...\endtitle* instructions for setting *\box\titlebox@* are
similar to those used for setting the *\vbox* in `*\HL@1*' (page~\ref{HLONE}),
except that we might as well follow other \amstex\ constructions and
 allow *\title* and *\endtitle* to
function separately, instead of having *\endtitle* be part of the syntax for
*\title*:
\footnote{There was really no point doing that for *\HL...\endHL*,
since something like *\chapter"allowbreak..."allowbreak\endchapter* would
have to be defined in terms of *\HL...\endHL* anyway.} 
\C**
\def\title{\begingroup\Let@
 \global\setbox\titlebox@=\vbox\bgroup\tabskip\hss@
 \halign to\hsize\bgroup
  \bf\hfil\ignorespaces##\unskip\hil\cr}
"slip
\def\endtitle{\crcr\egroup\egroup\endgroup
 \overlong@false}
**

Although *\maketitle* is going to print *\box\titlebox@* even if it is empty
(the idea is to leave some space for a hand-written title, or perhaps a title
with some weird special symbols, etc.), no author information is going to be
printed unless *\author"allowbreak..."allowbreak\endauthor* explicitly
appears. 

The definition of *\author* is exactly analogous to the definition of
*\title*, 
\C**
\newbox\authorbox@
\rightadd@\author\to\overlonglist@
\def\author{\begingroup\Let@
 \global\setbox\authorbox@=\vbox\bgroup\tabskip\hss@
 \halign to\hsize\bgroup
  \rm\hfil\ignorespaces##\unskip\hfil\cr}
\def\endauthor{\crcr\egroup\egroup\endgroup
 \overlong@false}
**
except that initially *\box\authorbox@* will be void; thus, *\maketitle*
 will be able
to use the test *\ifvoid\authorbox@* to tell whether *\author* has been
used. *\rm* was added just in case some other font has already been selected,
for some weird reason.

And *\affil* is exactly analogous:
\C**
\newbox\affilbox@
\def\affil{\begingroup\Let@
 \global\setbox\affilbox@=\vbox\bgroup\tabskip\hss@
 \halign to\hsize\bgroup
  \rm\hfil\ignorespaces##\unskip\hfil\cr}%
\def\endaffil{\crcr\egroup\egroup\endgroup
 \overlong@false}
**

*\date* is a little different, since we don't create a box.  Instead,
we define *\date@*, initially set equal to *\relax*:
\C**
\let\date@=\relax
\def\date#1{\gdef\date@{\ignorespaces#1\unskip}}
**
We add the appropriate *\ignorespaces* and
*\unskip* at this stage, since that is 
much easier than trying to insert them into
an already defined *\date@* later on.

The definition of *\today* is taken right from {\it The \tex book} (page~406):
\C**
\def\today{\ifcase\month\or January\or February\or
 March\or April\or May\or June\or July\or August\or
 September\or October\or November\or December\fi
 \space\number\day, \number\year}
**

And then, finally, *\maketitle* simply puts everything together.
We use 
**
\hrule \height0pt \vskip-\topskip
**
to get to the very top of the page, and then
**
\vskip24pt plus12pt minus12pt
\unvbox\titlebox@
**
to put  (stretchable) space before the (possibly empty) title. Then
we add some more space and the author(s), but only if there are some,
**
\ifvoid\authorbox@\else 
 \vskip12pt plus6pt minus3pt\unvbox\authorbox@ \fi
**

The affiliation and date are handled similarly, except that the date
is put inside a *\centerline* (with *\rm* explicitly stated).
 And then, finally, some extra space is added
before the first material of the document proper:
\C**
\def\maketitle{\hrule \height0pt \vskip-\topskip
 \vskip24pt plus12pt minus12pt
 \unvbox\titlebox@
 \ifvoid\authorbox@ \else
   \vskip12pt plus6pt minus3pt \unvbox\authorbox@ \fi
 \ifvoid\affilbox@ \else
   \vskip10pt plus5pt minus2pt \unvbox\affilbox@ \fi
 \ifx\date@\relax\else
  \vskip6pt plus2pt minus1pt \centerline{\rm\date@} \fi
 \vskip18pt plus12pt minus6pt}
**




\chapter The bibliography\label{MAKEBIB}\endchapter
\lamstex's bibliography constructions, an extension of those
originally used in *amsppt.sty*,
are really quite adequate for most bibliography requirements.  They show that
 various ``fields'' of
information, allowed to appear in any order, can be put together properly by
\tex\ itself, without resorting to an external program like \bibtex@.
Moreover, as explained on page~98 of the
\lamstex~Manual, the bibliographic entries can be labelled, and thus cited
within the text using *\ref*, so that the proper number for a bibliographic
entry is printed automatically (after enough passes).

Of course,
 \bibtex\ also allows  bibliographic entries to be selected from
 a data base and sorted in any of numerous desired ways.
  Moreover, the \bibtex\ approach has the advantage that the final
result (the *.bbl* file) consists of standard  (well, almost
standard) \tex\ code, and is thus easily edited and modified. By contrast, it
 may be quite
difficult to coerce \lamstex's bibliography macros into performing as
desired, and many special sorts of \tex\ trickery had to be built into the
macros for this purpose. (With either approach, careful proofreading of the
bibliography---rarely attempted by the authors, alas---is 
advisable, to check that
special situations have been handled correctly.

Since many people have already made extensive data bases for \bibtex@,
which they presumably don't want to go to waste,
 \lamstex\ now provides an interface with \bibtex@, as explained
in the next chapter. 
(Of course, it would be nice if there were a L{\eightrm IB}\kern-1pt
 \tex\ program,
working like \bibtex@, but producing a *.bbl* file with \lamstex\ code
instead of \latex\ code.)

Others may prefer using \lamstex's  bibliography macros, however,
especially since they provide features missing from \bibtex@.  I have added
all features  that the AMS has added to
*amsppt.sty* (though often with modified syntax),
 not to mention a few more of my own. All in all, this was a
rather harrowing experience---I now understand the perils of creeping
featureism. I ended up deferring the bibliography macros to the very
end, rightly dreading all the details that would be involved. On the other
hand, when I finally came to writing this chapter, it turned out that
the description of the macros, and the strategy behind them, went rather
smoothly. 

Most important of all, from the point of view of the user or style file
designer, once \lamstex's hidden macros have taken
 care of all the messy details,
the final process of printing the information from all the fields, in the
proper order, and with proper punctuation and spacing, is fairly
straightforward, and thus easily modified if some other sort of arrangement
is needed.


\section{\CS{cite}}
The *amsppt.sty* has  a *\cite* construction, which simply prints its
argument within brackets.  When we are interfacing with \bibtex@,
*\cite* will work essentially the same as in \latex@, but we will first give a
default definition. We will still allow *\cite* to producing something like
[Knuth1984, page~123], but the syntax for indicating the additional
information `page~123' will be changed, to
**
\cite(page~123){Knuth1984}
**
This is close  to \latex's
**
\cite[page~123]{...}
**
syntax for optional arguments; however the use of the brackets has been
avoided because they represent letters on Scandinavian keyboards. Of course,
any *)*'s in the additional text must be hidden in braces,
\setbox0\hbox{[\bf\dots{} \rm, section 1(a)]}
**
\cite({section 1(a)}){...}        "box0
**


There's nothing very surprising about the definition of *\cite*,
 which uses standard
techniques: 
\C**
\def\cite{%
 \def\nextii@(##1)##2{{\rm[}{##2}, {##1\/}{\rm]}}%
 \def\nextiii@##1{{\rm[}{##1\/}{\rm]}}%
 \def\next@{\ifx\next(\expandafter\nextii@\else
  \expandafter\nextiii@\fi}%
 \futurelet\next\next@}
**

\small Note that we always specify *\rm* [ and ]. We put *##1* and *##2*
inside braces, in case a font change instruction is added. (When we
are interfacing with \bibtex@, a font change instruction will only be
allowed in the optional argument *#1* (see page~\ref{OPARGCITE}).
\endsmall

\catcode`\@=11
\newif\ifaltcrop@
\def\topbibcrop@{\hbox{\smash{\dimen@\hsize\ifaltcrop@
 \advance\dimen@13pt\else\advance\dimen@8pt\fi
 \hbox to\dimen@{\vrule \height0pt depth5pt width.4pt
  \hskip-.4pt\vrule \height.4pt depth0pt width5pt \hfil
 \vrule \height.4pt depth0pt width5pt \hskip-.4pt
  \vrule \height0pt depth5pt width.4pt}}}}
\def\botbibcrop@{\hbox{\smash{\dimen@\hsize\ifaltcrop@
 \advance\dimen@13pt\else\advance\dimen@8pt\fi
 \hbox to\dimen@{\vrule \height5pt depth0pt width.4pt
 \hskip-.4pt\vrule \height.4pt depth0pt width5pt\hfil
 \vrule \height.4pt depth0pt width5pt \hskip-.4pt
  \vrule \height5pt depth0pt width.4pt}}}}
\def\bibcrop@#1{\vbox{\topbibcrop@\vbox{\vskip5pt
 \hbox{\ifaltcrop@\hskip5pt\fi
 #1\hskip3pt}\vskip3pt}\vskip-\baselineskip\botbibcrop@}}
\def\showbib#1\endbib{\medskip\setbox0\vbox{%
 \sfcode`\.=\@m\def\nopunct{\nopunct@true}%
 \def\nospace{\nospace@true}%
 \def\nakerns@{\null\kern\m@ne sp\kern\@ne sp}%
 \def\lkerns@{\null\kern-\tw@ sp\kern\tw@ sp}%
 \def\nkerns@{\null\kern-\thr@@ sp\kern\thr@@ sp}\bib#1\endbib}%
 \centerline{\bibcrop@{\box0}\ifaltcrop@\hskip5pt\fi}%
 \medskip\altcrop@false}
\def\altshowbib{\altcrop@true\showbib}
\catcode`\@=\active



\section{Features of \lamstex's bibliography macros}
The original *amsppt.sty* command *\Refs* is called
**
\makebib
**
in \lamstex@, and this *\makebib* now requires a matching
**
\endmakebib
**
at the end of the entries. With the 
**
\makebib
 . . .
\endmakebib
**
region,
the general *amsppt.sty* syntax
**
\ref ... \endref
**
has been changed to
**
\bib ... \endbib
**
since *\ref* already has another use in \lamstex@.

Within *\bib...\endbib* we can use the fields
**
\no \key 
\by \bysame 
\paper \jour \vol \issue \yr \toappear
\pg \pp 
\book \inbook \publ \publaddr 
\paperinfo \bookinfo \finalinfo
**
which correspond to those
from the original *amsppt.sty*, with *\pg* and *\pp* replacing *\page* and
*\pages*, since *\page* has another use in \lamstex.

Some changes have been made in conformity with changes by the AMS@:
\bullist
\item 
*\key* now automatically adds brackets, and sets its field in *\bf*. 
Thus, *\key C1* gives `[{\bf C1}]', which was  previously 
 typed as *\key \bf C1*.
\item
*\inbook* normally
prints only the book title, not preceded by `in~' [which many people don't
like very much], although, as discussed below, this can be changed.
\item
*\issue* now prints `no. ' before its field, 
 though I think that's very bad (*\issue* was originally designed
for something like `Special commemorative issue'). 
\item
The AMS has also changed\pagelabel{USEFINFO}
*\finalinfo*, so that it is preceded by a comma, rather than a period after
all the previous information.  I think that's even worse, and have
kept the old arrangement (see page~\ref{FINFO} for further discussion of this
particular point.)
\endbullist

As in the AMS's new *amsppt.sty*, there is no longer a *\manyby* to indicate
the start of a sequence of *\bysame*'s.  The first reference is simply
typed as *\by*, with *\bysame* used for the subsequent ones.  In addition,
*\bysame* now prints a horizontal rule of fixed width, rather than one that
varies with the width of the first instance. (This makes the macros
considerably easier to write, but it's what journals always use anyway, so
there's no point apologizing for the shortcut.)

*\moreref* has been changed to *\morebib*. As before, something like
**
\bib \no 2 \by L. Auslander
\paper On the Euler characteristic of 
 compact locally affine spaces
\jour Comment. Math. Helv. \vol 35 \yr 1961 \pp25--27
\morebib
\paper \rm II 
\jour Bull. Amer. Math. Soc. \vol67 \yr1961 \pp 405--406
\endbib
**
will produce
\showbib
\no 2
\by L. Auslander
\paper On the Euler characteristic of 
 compact locally affine spaces
\jour Comment. Math. Helv. \vol 35 \yr 1961 \pp25--27
\morebib
\paper \rm II 
\jour Bull. Amer. Math. Soc. \vol67 \yr1961 \pp 405--406
\endbib


If part II of this paper had appeared in the same journal, but in a different
volume,
**
\bib \no 2 \by L. Auslander
\paper On the Euler characteristic of 
 compact locally affine spaces
\jour Comment. Math. Helv. \vol 35 \yr 1961 \pp25--27
\morebib
\paper \rm II 
\vol36 \yr1961 \pp 13--15
\endbib
**
the output would look like
\showbib
\no 2
\by L. Auslander
\paper On the Euler characteristic of compact locally affine spaces
\jour Comment. Math. Helv. \vol 35 \yr 1961 \pp25--27
\morebib
\paper \rm II 
\vol36 \yr1961 \pp 13--15
\endbib


\noindent*\morebib* remembers that there was a *\jour* before, so it prints
the *\vol*, *\yr*, and *\pp* fields for the second title even though no
*\jour* is given for that title. 

By the way, this example
illustrates one of those
innumerable circumstances where a completely automated system won't give the
optimal results:  journal volume numbers in the default style
happen to be printed without commas following the preceding field, which
looks just fine for the {\bf35} following\linebreak
 `Comment. Math. Helv.', but not so fine
after the shortened title `II'; in this case we would probably want to change
the input to
**
\paper \rm II, "8COMNO"8
**
(see also page~\ref{UCOMNO}).

\medbreak

This ``remembering'' feature of *\morebib*
is generally quite convenient, but it doesn't
give the desired results in certain other situations. For example,
**
\bib
\no 3 \by Stefan Banach
\paper Sur la d\'ecomposition des ensembles de points 
 en parties respectivement congruents
\jour Fund. Math. \vol 6 \yr 1925 \pp 244--277
\morebib 
\book \OE uvres
\publ \'Editions Scientifiques de Pologne
\publaddr Warzaw \yr 1967
\endbib
**
will produce
\showbib
\no 3 \by Stefan Banach
\paper  Sur la d\'ecomposition des ensembles de points en parties
respectivement congruents
\jour Fund. Math. \vol 6 \yr 1925 \pp 244--277
\morebib 
\book \OE uvres
\publ \'Editions Scientifiques de Pologne
\publaddr Warzaw \yr 1967
\endbib
\noindent Here the 1967 got printed first, as if it were the *\yr* for a
*\jour*, because *\morebib* remembered that a *\jour* appeared before.


So there is now *\anotherbib*, which clears out such information. If we use
*\anotherbib* instead of *\morebib* we will get the desired result:
\showbib
\no 3\by Stefan Banach
\paper Sur la d\'ecomposition des ensembles de points en parties
respectivement congruents
\jour Fund. Math. \vol 6 \yr 1925 \pp 244--277
\anotherbib
\book \OE uvres
\publ \'Editions Scientifiques de Pologne
\publaddr Warzaw \yr 1967
\endbib


By the way, the AMS does not seem to have retained this ``remembering''
feature for *\morebib*. At any rate, the
 \amstex~Version 2.0 User's Guide gives an example
like
**
\bib \no 7
\by P. D. Lax and C. D. Levermore
\paper The small dispersion limit for the KdV equation.~\rm I
\jour Comm. Pure Appl. Math. \vol 36 \yr1983
\pp 253--290 
\morebib\paper \rm II
\jour Comm. Pure Appl. Math.
\vol 36 \yr 1983 \pp 571--594
\morebib\paper \rm III
\jour Comm. Pure Appl. Math.
\vol 36 \yr 1983 \pp 809--829
\endbib
**
to produce
\showbib \no7
\by P. D. Lax and C. D. Levermore
\paper The small dispersion limit for the KdV equation.~\rm I
\jour Comm. Pure Appl. Math. \vol 36 \yr1983
\pp 253--290 
\morebib\paper \rm II
\jour Comm. Pure Appl. Math.
\vol 36 \yr 1983 \pp 571--594
\morebib\paper \rm III
\jour Comm. Pure Appl. Math.
\vol 36 \yr 1983 \pp 809--829
\endbib
\noindent which is an obvious example of overkill. The listing
\showbib \no 7
\by P. D. Lax and C. D. Levermore
\paper The small dispersion limit for the KdV equation.~\rm I
\jour Comm. Pure Appl. Math. \vol 36 \yr1983
\pp 253--290 
\morebib\paper \rm II
\pp 571--594
\morebib\paper \rm III
\pp 809--829
\endbib
\noindent would have been preferable by far.

\bigskip

There are now four new fields, as added by the AMS@:
\bullist
\item
*\ed* and *\eds* are for one editor, or several editors, respectively, of a
book; the first adds ``ed\.'' after the editor's name, while the
second adds ``eds''; all the information is enclosed in parentheses.
\item
 *\lang*, for the original language of a translation, prints its
information, enclosed in parentheses,
 at the very end, after the final punctuation for the *\bib*
entry. I have followed the AMS macros in this
regard---*\lang* basically becomes *\finalinfo*---although I don't think
that's 
the optimal solution.
\item
 *\transl* is for translation information,
preceding the *\jour* or *\book* to which it pertains; thus, an entry with
*\transl* may well have more than one *\jour* or *\book*---in essence,
*\transl* functions something like *\anotherbib*.
\endbullist
\medskip

\noindent As examples,
**
\bib\no9 \by S. Kripke   "8Kripke"8
\paper Semantical analysis of intuitionistic logic \rm I
\inbook Formal Systems and Recursive Functions
\eds J. Corssely and M. A. E. Dummett
\publ North-Holland \yr1965 \pp92--130 
\endbib
**
produces
\showbib
\no9 \by S. Kripke
\paper Semantical analysis of intuitionistic logic \rm I
\inbook Formal Systems and Recursive Functions
\eds J. Corssely and M. A. E. Dummett
\publ North-Holland \yr1965 \pp92--130 
\endbib
and
**
\bib\no6 \by O. A. Ladyzhenskaya
\book Mathematical problems in the dynamics of a viscous 
incompressible fluid \bookinfo 2nd rev. aug. ed.
\publ ``Nauka'' \publaddr Moscow \yr 1970
\lang Russian
\transl English transl. of 1st ed.
\book The mathematical theory of viscous
 incompressible flow
\publ Gordon and Breach \publaddr New York
\yr 1963; rev. 1969
\endbib
**
produces
\showbib
\no6 \by O. A. Ladyzhenskaya
\book Mathematical problems in the dynamics of a viscous 
incompressible fluid \bookinfo 2nd rev. aug. ed.
\publ ``Nauka'' \publaddr Moscow \yr 1970
\lang Russian
\transl English transl. of 1st ed.
\book The mathematical theory of viscous
 incompressible flow
\publ Gordon and Breach \publaddr New York
\yr 1963; rev. 1969
\endbib



As you can see from these examples, 
the default style, in conformity with the AMS's changes,
 now prints both paper titles and book titles in italics,
except for book titles produced by *\inbook*.
However,  there are new AMS constructions
**
\bookinquotes
\paperinquotes
**
which 
have also been added in \lamstex@.  Typing
**
\bookinquotes
**
after *\makebib*
will cause all the book entries to be placed in quotes (and in roman type),
 and similarly for *\paperinquotes*.


\medskip

*\paperinquotes* and *\bookinquotes* can be used together, but
I personally feel that 
one, and only one, of
these commands should always be used,
 to distinguish between papers and books. The necessity for
this is well illustrated by
one of the AMS's examples in the User's Guide:
\showbib
\no 4 \by V. I. Arnol$'$d, A. N. Varchenko, and S. M. Guse\u\i n-Zade
\book Singularities of differentiable maps.~\rm I
\publ ``Nauka'' \publaddr Moscow \yr 1982
\lang Russian
\endbib
\noindent
Until I looked at the input,
**
\bib \no 4 \by V. I. Arnol$'$d, A. N. Varchenko, 
 and S. M. Guse\u\i n-Zade
\book Singularities of differentiable maps.~\rm I
\publ ``Nauka'' \publaddr Moscow \yr 1982
\lang Russian
\endbib
**
I didn't know this was a book! (Normally a book would have something 
like `Volume~1' in its title.)

\medskip 

The Kripke example on page~\ref{Kripke}  appears on
page~ 263 of the second edition of {\it The Joy of \tex}, but with
**
\inbook in Formal Systems and Recursive Functions
**
to explicitly add `in~' before the book title.  Unfortunately, that won't
work very well if *\bookinquotes* has been specified!  Instead, I have added 
**
\ininbook
**
to add `in~' before all book titles specified by
*\inbook*; if *\bookinquotes* has also 
been specified, the quotes will go only
around the book title itself.

\medskip

The AMS has extended the use of (the old) *\nofrills* within the
bibliography: *\nofrills* after a field suppresses the punctuation that would
normally occur. The above mentioned example was actually given as
**
\bib
\no9 \by S. Kripke
\paper\nofrills Semantical analysis of 
 intuitionistic logic \rm I;
\inbook in Formal Systems and Recursive Functions
\eds J. Corssely and M. A. E. Dummett
\publ North-Holland \yr1965 \pp92--130 
\endbib
** 
to produce
\showbib
\no9 \by S. Kripke
\nopunct\paper Semantical analysis of intuitionistic logic \rm I;
\inbook in Formal Systems and Recursive Functions
\eds J. Corssely and M. A. E. Dummett
\publ North-Holland \yr1965 \pp92--130 
\endbib

*\nofrills* has been replaced by *\nopunct* and *\nospace* in \lamstex\ (and
its positioning has been changed), and this usage now extends to bibliography
items also: In \lamstex\ 
the above example could be typed as
**
\ininbook
"slip
\bib
\no9 \by S. Kripke
\nopunct\paper Semantical analysis of 
 intuitionistic logic \rm I;
\inbook  Formal Systems and Recursive Functions
\eds J. Corssely and M. A. E. Dummett
\publ North-Holland \yr1965 \pp92--130 
\endbib
**

Note that on page~\ref{COMNO} we might use
**
\nopunct \paper \rm II, "8UCOMNO"8
**
if we weren't sure about the treatment of punctuation for the next field.

\medbreak

The AMS also allows *\nofrills* to occur before a field name, in order to
suppress punctuation after the {\it previous\/} field.  For \lamstex@, where
*\nopunct* and *\nospace* always precede the fields, I have added
**
\noprepunct
\noprespace
**
For example, 
to print
\showbib \no 7
\by P. D. Lax and C. D. Levermore
\paper The small dispersion limit for the KdV equation.~\rm I
\jour Comm. Pure Appl. Math. \vol 36 \yr1983
\pp 253--290 
\noprepunct\finalinfo (overview)
\morebib\paper \rm II
\pp 571--594
\morebib\paper \rm III
\pp 809--829
\endbib
\noindent we can use
**
\bib \no 7
\by P. D. Lax and C. D. Levermore
"2
\paper The small dispersion limit for the KdV equation.~\rm I
"2
\jour Comm. Pure Appl. Math. \vol 36 \yr1983
"2
\pp 253--290 
"2
\noprepunct\finalinfo (overview)
"2
\morebib\paper \rm II
"2
\pp 571--594
"2
\morebib\paper \rm III
\pp 809--829
\endbib
**
thereby suppressing the punctuation on the field 
 immediately preceding the *\finalinfo* (we might not be sure
just which field this is).

As another example,\pagelabel{FINFO} note that in \lamstex\ the input
**
\bib
\key C \by H. Cartan
\paper Operations dans les construction acycliques 
\inbook Seminaire H. Cartan 1954--55
\bookinfo Expos\'e 6 \publ ENS \publaddr Paris
\finalinfo Reprinted by W. A. Benjamin, New York (1967)
\endbib
**
produces
\altshowbib
\key C \by H. Cartan
\paper Operations dans les construction acycliques 
\inbook Seminaire H. Cartan 1954--55
\bookinfo Expos\'e 6 \publ ENS \publaddr Paris
\finalinfo Reprinted by W. A. Benjamin, New York (1967)
\endbib
\noindent with the information from the
*\finalinfo* field following a period after all the other fields
(see page~\ref{USEFINFO}).  To print this in the AMS's manner,
\altshowbib
\key C\by H. Cartan
\paper Operations dans les construction acycliques 
\inbook Seminaire H. Cartan 1954--55
\bookinfo Expos\'e 6 \publ ENS \publaddr Paris
\noprespace\noprepunct\finalinfo
 , reprinted by W. A. Benjamin, New York (1967)
\endbib
\noindent we can type
**
 . . .
\publ ENS \publaddr Paris
\noprespace\noprepunct\finalinfo  , reprinted by
 W. A. Benjamin, New York (1967).
\endbib
**

Notice also 
that, once again in conformity with the AMS's changes, 
 punctuation  is supplied automatically after *\finalinfo*,
unless it is preceded by *\nopunct*.

\medskip

Finally, it turned out that one more such modifier was needed.  When book
or paper titles are printed in quotes, we sometimes want to suppress the
quotation marks.  For example,
{\paperinquotes
\showbib
\no2\by L. Auslander
\paper On the Euler characteristic of compact locally affine spaces
\jour Comment. Math. Helv. \vol 35 \yr 1961 \pp25--27
\morebib
\paper \rm II 
\jour Bull. Amer. Math. Soc. \vol67 \yr1961 \pp 405--406
\endbib
\noindent
looks much better if we suppress the quotations around the II,
\showbib
\no2
\by L. Auslander
\paper On the Euler characteristic of compact locally affine spaces
\jour Comment. Math. Helv. \vol 35 \yr 1961 \pp25--27
\morebib
\noquotes\paper \rm II 
\jour Bull. Amer. Math. Soc. \vol67 \yr1961 \pp 405--406
\endbib
\noindent To obtain this, we would type
**
\morebib
\noquotes\paper \rm II
 . . .
**

}

\section{Storing the fields\label{BASICD}}
One of
the basic problems in the bibliography macros is that we want
to be able to type things like
**
 \by ... \paper ... \jour ...
**
instead of
**
 \by {...} \paper {...} \jour {...}
**
but we also don't want to force the various elements to be typed in a
particular order, or force all of them to appear.  

The solution to this problem is to have boxes, say *\bybox@*, *\paperbox@*,
*\jourbox@*, \dots, in which to store the information from these various
fields, and to make definitions like
**
\def\by{\unskip\egroup \setbox\bybox@=\hbox\bgroup}
\def\paper{\unskip\egroup \setbox\paperbox@=\hbox\bgroup}
**
The idea is that the *\egroup* matches the *\bgroup* from the previous field,
and then we start storing the current field. (The *\unskip* before the
*\egroup* simply removes any extraneous space at the end of the previous
field; it is convenient to get rid of this space at the very outset, instead
of worrying about it later.) 
 The definition of
*\bib* will have to start with an extra *\bgroup*, which will  be
closed by the *\egroup* of the first field that follows, while *\endbib* will
 supply a final *\egroup*, and then take the material in all these
boxes, and suitably arrange them.

This whole idea works because *\hbox* can be ended by *\egroup*, rather
than an explicit~*}*.
However, several details intrude:

\Pitem If the user adds one of the 
 line breaking commands, *\nolinebreak*,\linebreak
*\allowlinebreak*, *\linebreak*, or *\newline* at the end of a field, we
want the corresponding *\penalty* to be inserted {\it after\/} the
punctuation that will follow the field when it is printed, not before.

Recall (section~\Sref{LBK})
that the \lamstex\ definitions of *\nolinebreak*,\linebreak
 *\allowlinebreak*, and *\linebreak*
 have an extra element *\lkerns@* at the end, while
 *\newlines* has *\nkerns@*.  Originally these
are both *\relax*, but now we will change them, so that they involve very
small kerns like
**
\kern-1sp \kern1sp
**
The presence of such *\kern*'s, presumably not ever explicitly inserted by
the user, will allow us to recognize that such commands were typed, and to
deal
with them suitably (details are presented in section~\Sref{VBOXI}).

\pitem Some people like to prepare a ``template'' with all possible fields,
**
\bib 
\no
\key
\paper
 . . .
**
and then fill in only the necessary fields. So we have to deal with the
possibility that certain fields are empty.\pagelabel{EFIELD}

\pitem Finally, there is the phenomenon reported by Michael Downes 
in TUG{\ninerm BOAT}, Volume~11, No.~4.  Normally when \tex\ is setting
text it inserts a discretionary break after hyphens, en- and em-dashes,
and explicitly typed discretionary hyphens~*\-*. But these are omitted
when setting an *\hbox*
(in restricted horizontal mode).  If the *\hbox* is later *\unhbox*'ed, and
made part of a paragraph, \tex\ will attempt hyphenation, as usual, if it
can't set the paragraph without hyphenation. But when this second attempt is
made, hyphenations are inserted only by the hyphenation algorithm---possible
break points after hyphens, 
dashes and discretionary hyphens are not added at this
stage. Since the possible break points after hyphens, dashes and
discretionary hyphens weren't added in the original *\hbox*, they have thus
been
lost forever.  So, for example, a compound word like ``Nebraska--Lincoln''
will not be able to break properly at the end of a line.

The solution to this problem will be to set everything as a *\noindent*'ed
paragraph within a *\vbox*
with *\hsize=\maxdimen*, and then take the *\vbox* apart.
So we will be using definitions like
\Litbox0=**
\def\paper{\unskip\egroup
 \setbox\paperbox@=\vbox\bgroup \hsize=\maxdimen }
**
$$\pagelabel{BASICA}\vcenter{\box0}\tag"\style{\bf A}"$$ 

In this situation,  line breaking commands at the end of a field have
to be handled a bit differently. We will add things like
**
\null\kern-1sp\kern1sp
**
so that the *\null* will keep the *\kern*'s from disappearing at the end of
the line.


\section{Starting the bibliography macros\label{SBMACS}}
The definition of *\makebib* begins
**
\def\makebib@W{Bibliography}
"slip
\def\makebib{\begingroup
 \rm
 \bigbreak
 \centerline{\smc\makebib@W}
 \nobreak\medskip
 \sfcode`\.=1000 \everypar={}\parindent=0pt
**
We use *\makebib@W* instead of specifying `*Bibliography*' explicitly,
so that *\newword\makebib* can be used to change this heading 
(compare section~\Sref{OTHERE} and Chapter~\ref{acces}). *\rm* is added, just
in case another font has been selected.
The space factor code of the period is changed 
to ~*1000* because almost all periods in a bibliography will come from
abbreviations (except for the periods at the ends of each entry, and those
 occur at the
ends of paragraphs). We add *\everypar={}* \pagelabel{EVAPI}
just in case *\everypar* was
non-empty before, since each entry begins as a nonindented paragraph, and we
might as well set *\parindent* to~*0pt*, though that shouldn't matter.

Once *\makebib* has appeared, we might be using not only *\nopunct* and
*\nospace*, but also *\noprepunct* and *\noprespace* and
*\noquotes* 
before various elements
of a *\bib...\endbib* entry.
Since all of these can precede almost any construction, 
 we want to save
ourselves all the agony of section~\Sref{AGONY}, and simply have each of
these set a flag.  *\nopunct* and *\nospace*, which already have definitions,
will thus have to be changed by *\makebib*, and, to be on the safe side,
we will reset the flags  to  be false,
**
\def\makebib{\bigbreak
 \centerline{\smc Bibliography}
 \nobreak\bigskip
 \sfcode`\.=1000 \everypar={}\parindetn=0pt
 \def\nopunct{\nopunct@true}
 \def\nospace{\nospace@true}
 \nopunct@false\nospace@false
**

As mentioned in section~\Sref{BASICD}, *\lkerns@*, and
*\nkerns@*
 have to be changed for the bibliography macros; these
new definitions also have to be added to *\makebib*:
\C**
\def\makebib{\bigbreak
 \centerline{\smc Bibliography}%
 \nobreak\bigskip
 \sfcode`\.=1000 \everypar={}\parindent=0pt
 \def\nopunct{\nopunct@true}%
 \def\nospace{\noprepunct@true}%
 \nopunct@false\nospace@false
 \def\lkerns@{\null\kern-1sp\kern1sp}%
 \def\nkerns@{\null\kern-2sp\kern2sp}%
}
**

The *\endmakebib* simply supplies the *\endgroup* that matches the\linebreak
*\begingroup* with which *\makebib* begins:
\C**
\let\endmakebib=\endgroup
**

Next we add the flags and definitions
\C**
\newif\ifnoprepunct@
\newif\ifnoprespace@
\newif\ifnoquotes@
"2
\def\noprepunct{\noprepunct@true}
\def\noprespace{\noprespace@true}
\def\noquotes{\noquotes@true}
**

And then we declare all the boxes needed to hold various constructions:
\C**
\newbox\nobox@
\newbox\keybox@       
\newbox\bybox@
"2
\newbox\paperbox@
\newbox\paperinfobox@
"2
\newbox\jourbox@
\newbox\volbox@ 
\newbox\issuebox@
\newbox\yrbox@
"2
\newbox\pgbox@
\newbox\ppbox@
"2
\newbox\bookbox@ 
\newbox\inbookbox@
\newbox\bookinfobox@
"2
\newbox\publbox@
\newbox\publaddrbox@ 
"2
\newbox\edbox@
\newbox\edsbox@
"2
\newbox\langbox@
\newbox\translbox@
\newbox\finalinfobox@
**

\section{\CS{bibinfo\@}\label{BIBINFO}}
Each of 
 various constructions within a *\bib...\endbib* entry, like
*\paper*, *\jour*, \dots, 
may be preceded by *\nopunct*,\dots,\linebreak
 *\noquotes*, and we need an easy
way to keep track of this information.
We will store all the
necessary information for a *\bib...\endbib* entry
in a control sequence *\bibinfo@* (initially empty at the beginning of each
*\bib*).
Each field like *\paper*, *\jour*, \dots, will first update *\bibinfo@*,
based on the current values of the flags *\ifnopunct@*, \dots,
*\ifnoquotes@*---these values will simply depend on whether *\nopunct*, \dots,
*\noquotes* occurred before this field (but after the preceding field).

 Remember that 
 *\paperbox@*, *\jourbox@*, \dots, are simply \tex\ integers, 
\footnote{More precisely
({\it The \tex book}, page~121),
the *\newbox* routine will *\chardef\paperbox@*, etc., and \tex\ allows
*\chardef*'d quantities to be used as integers.}
which we can produce with
 *\the\paperbox@*, 
*\the\jourbox@*, \dots. If\linebreak
 *\paperbox@*
happens to have the value ~*28* (it did the last time I checked), and 
*\jourbox@* happens 
to have the value ~*30*, and *\paper* and *\jour* are preceded by 
any of *\nopunct*, \dots, *\noquotes*, then we want *\bibinfo@* to be
\setbox1\hbox{$_{\text1}$}\setbox2\hbox{$_{\text2}$}
\setbox3\hbox{$_{\text3}$}\setbox4\hbox{$_{\text4}$}
\setbox5\hbox{$_{\text5}$}
**
28,x"copy1"relax"0x"copy2"relax"0x"copy3"relax"0x"copy4"relax"0x"copy5"relax"030,y"copy1"relax"0y"copy2"relax"0y"copy3"relax"0y"copy4"relax"0y"copy5
**
\setbox1\hbox{$_{\text1}$}\setbox2\hbox{$_{\text2}$}%
\setbox3\hbox{$_{\text3}$}\setbox4\hbox{$_{\text4}$}%
\setbox5\hbox{$_{\text5}$}%
$\bigl[$or
*30,y"copy1"relax"0y"copy2"relax"0y"copy3"relax"0y"copy4"relax"0y"copy5"relax"028,x"copy1"relax"0x"copy2"relax"0x"copy3"relax"0x"copy4"relax"0x"copy5
*
if *\jour* appears before *\paper*$\bigr]$,
where 
\setbox7\hbox{$_{\text1}$}\setbox2\hbox{$_{\text2}$}
\setbox3\hbox{$_{\text3}$}\setbox4\hbox{$_{\text4}$}
\setbox5\hbox{$_{\text5}$}
$$\align
 \text{{\tt x}\copy7\quad is\quad}&
 \cases {\tt1}&\text{if {\tt\bs nopunct} precedes
  {\tt\bs paper}}\\
  {\tt0}&\text{otherwise}\endcases\\
\allowdisplaybreak
 \text{{\tt x}\copy2\quad is\quad}&
 \cases {\tt1}&\text{if {\tt\bs nospace} precedes
  {\tt\bs paper}}\\
  {\tt0}&\text{otherwise}\endcases\\
\allowdisplaybreak
 \text{{\tt x}\copy3\quad is\quad}&
  \cases {\tt1}&\text{if {\tt\bs noprepunct} precedes
  {\tt\bs paper}}\\
  {\tt0}&\text{otherwise}\endcases\\
\allowdisplaybreak
 \text{{\tt x}\copy4\quad is\quad}&
  \cases{\tt1}&\text{if {\tt\bs noprespace} precedes
  {\tt\bs paper}}\\
  {\tt0}&\text{otherwise}\endcases\\
\allowdisplaybreak
 \text{{\tt x}\copy5\quad is\quad}&
  \cases {\tt1}&\text{if {\tt\bs noquotes} precedes
  {\tt\bs paper}}\\
  {\tt0}&\text{otherwise}\endcases
\endalign$$
and similarly for *y*\copy7, \dots, *y*\copy5.
 

To conserve memory,  and allow subsequent macros to work quickly,
we want *\bibinfo@* to contain only necessary information; boxes not preceded
by any of
*\nopunct*, \dots, *\noquotes* simply shouldn't show up.


The routine *\setbibinfo@#1*, used when *#1* is *\paperbox@*, \dots, 
suitably expands *\bibinfo@* if necessary, based on the current
values of
the flags *\ifnopunct@*, \dots, *\ifnoquotes@*:
\C**
\def\setbibinfo@#1{\edef\next@{\ifnopunct@1\else0\fi
 \ifnospace@1\else0\fi\ifnoprepunct@1\else0\fi
 \ifnoprespace@1\else0\fi\ifnoquotes@1\else0\fi}%
 \def\nextii@{00000}%
 \ifx\next@\nextii@
 \else
  \xdef\bibinfo@{\bibinfo@\the#1,\next@}%
 \fi}
**
\setbox1\hbox{$_{\text1}$}\setbox2\hbox{$_{\text2}$}%
\setbox3\hbox{$_{\text3}$}\setbox4\hbox{$_{\text4}$}%
\setbox5\hbox{$_{\text5}$}%
Here we first set *\next@* to the proper *x*\copy1 \dots *x*\copy5.
Then, if this sequence is *00000* (because none of *\nopunct*, \dots,
*\noquotes* appeared) we do nothing; otherwise, we add
\setbox1\hbox{$_{\text1}$}\setbox2\hbox{$_{\text2}$}%
\setbox3\hbox{$_{\text3}$}\setbox4\hbox{$_{\text4}$}%
\setbox5\hbox{$_{\text5}$}%
**
\the#1,x"copy1x"copy2x"copy3x"copy4x"copy5
**
to *\bibinbfo@*. An *\xdef* was needed to define *\bibinfo@* globally
because we will be using *\setbibino@* within a group, to pass information on
beyond that group (section~\Sref{VBOXII}).

There is a corresponding *\getbibinfo@#1*, which will
*\let\next@=x*$_{\text1}$, 
 \dots,
*\let\nextv@=x*$_{\text5}$ when
 `*\the#1,*' appears in *\bibinfo@*, or simply *\let* them
 *=0* otherwise:
\C**
\def\getbibinfo@#1{%
 \ifx\bibinfo@\empty
  \let\next@=0\let\nextii@=0\let\nextiii@=0%
  \let\nextiv@=0\let\nextv@=0%
"2
 \else
  \edef\next@{\def
   \noexpand\next@####1\the
    #1,####2####3####4####5####6####7\noexpand\next@
    {\let\noexpand\next@=####2\let\noexpand\nextii@=####3%
    \let\noexpand\nextiii@=####4\let\noexpand\nextiv@=####5%
    \let\noexpand\nextv@=####6}%
   \noexpand\next@\bibinfo@\the#1,00000\noexpand\next@}%
  \next@
 \fi}
**
By now it should be no problem to unravel this (compare
page~\ref{ADDCSNAME} and Chapter~\ref{NEWC}).
For the sake of speed, we have made a special clause for the (usual) case
where *\bibinfo@* is empty.
We use the rather rare assignments *\let\next@=0* or *\let\next@=1*, etc.,
so that later we can use  simple *\if* tests,
**
\if\next@1  . . .
**
to test for the value.


Note, finally, that these definitions work because *\paperbox@*, \dots, all
represent 2@-digit numbers.  There would be ambiguity if, for example,
one had the value ~*9* and another had the value ~*19*; fortunately, that
can't happen, since *\newbox* only creates numbers greater than ~*9*.


\section{Additional flags}
Next we introduce the flags for determining the treatment of paper and
book titles:
\C**
\newif\ifbookinquotes@
\def\bookinquotes{\bookinquotes@true}
\newif\ifpaperinquotes@
\def\paperinquotes{\paperinquotes@true}
\newif\ifininbook@
\def\ininbook{\ininbook@true}
**

We will also need a flag
\C**
\newif\ifopenquotes@
**
which we will set true after printing each
 *\paper* or
*\book* title that has begun with~*``*.
The next field will then supply the closing~*''* at the right time,
and reset the flag to false,
 using
the routine
\C**
\def\closequotes@{\ifopenquotes@''\openquotes@false\fi} "8OQFALSE"8
**


In addition, we need special flags to deal with the possibilities of
*\morebib*, *\anotherbib*, and *\transl*.
The definitions of these constructions aren't given until
section~\Sref{ENDS}, but some discussion  is necessary
now. These three constructions act almost like an *\endbib*~ *\bib* pair,
first printing the information already collected (but without ending the
paragraph), and then collecting new information.  For efficiency, these
constructions and *\endbib* all
call upon a common construction, *\endbib@*, which
does all the work of printing the accumulated information, except that
certain flags will have to be set  differently for the various constructions.

First we have the flags
\C**
\newif\ifbeginbib@
\newif\ifendbib@
**
The flag *\ifbeginbib@* will, for example, determine whether or not we should
print *\no* and *\key* information; it will be true when we are
setting the first part of a *\bib...\endbib* entry, but false if we are
printing a *\morebib* part. The flag *\ifendbib@* will, for example,
determine whether we should print the final period at the end of the entry;
it will be false if we are printing the first part of an entry that has
a *\morebib* part to follow, though it will be true when we then set
the *\morebib* part.

We also need the flags
\C**
\newif\ifprevjour@
\newif\ifprevbook@
**
to pass information to *\morebib* and *\anotherbib* about a *\jour* or
*\book* in the main part.



\section{\CS{bib}}
For defining *\bib* we first introduce a new
dimension 
\C**
\newdimen\bibindent@
**
with the default value
\C**
\bibindent@=20pt
**
in terms of which the hanging indentation for *\bib* items will be
specified.  This makes it easier to add commands to change this indentation.
(The default style doesn't have any such commands, but other styles do.)
Then we define
\C**
\def\bib{\global\let\bibinfo@=\empty
 \global\let\translinfo@=\relax
 \beginbib@true
 \begingroup
 \noindent@\hangindent\bibindent@ \hangafter1
 \bib@} 
**
The *\global\let\bibinfo@=\empty* clears out *\bibinfo@* from the previous
*\bib..\endbib*. 
  *\translinfo@*, which will play a role later, also has
to be cleared out. Then we set *\ifbeginbib@* to be true, begin a group,
start a *\noindent@*'ed paragraph with hanging indentation *\bibindent@* after
the first line, and call *\bib@*.


*\bib@* has to start by setting *\nobox@*, *\keybox@*, \dots, to void boxes.
We introduce the abbreviation
\C**
\def\v@id#1{\setbox#1=\box\voidb@x}
**
and then 
\C**
\def\bib@{\v@id\nobox@ \v@id\keybox@ \v@id\bybox@
 \v@id\paperbox@ \v@id\paperinfobox@
 \v@id\jourbox@ \v@id\volbox@ \v@id\issuebox@ \v@id\yrbox@
 \v@id\pgbox@ \v@id\ppbox@
 \v@id\bookbox@ \v@id\inbookbox@ \v@id\bookinfobox@ 
 \v@id\publbox@ \v@id\publaddrbox@ 
 \v@id\edbox@ \v@id\edsbox@ 
 \v@id\langbox@ \v@id\translbox@ \v@id\finalinfobox@
 \bgroup}
**
As explained in section~\Sref{BASICD},
 the *\bgroup* will immediately be closed
by an *\egroup* at the beginning of the *\no* or *\key* or \dots\ that
occurs next.

\section{The basic construction}
The basic definition ({\bf A}) on page~\ref{BASICA} is going to be
changed in several ways.  First of all, when *#1* is *\paperbox@*,
*\jourbox@*, etc., 
we want to add
**
\unskip"9\setbibinfo@#1"9\egroup
\setbox#1=\vbox\bgroup . . .
**
so that *\bibinfo@* will have
 the proper information regarding any *\nopunct*, \dots, *\noquotes* that
precede *\paper*, *\jour*, \dots. Since the information in
 *\bibinfo@* is recorded using
*\xdef*'s, this can be done before the *\egroup*; note also that
since each *\nopunct*, \dots, *\noquotes* will occur within a field, and
thus eventually within some *\bgroup...\egroup*, we don't have to worry about
 their effects unexpectedly promulgating to another field.

Inside the *\vbox* we will want to have
**
\hsize=\maxdimen
**
as well as
**
\leftskip=0pt \rightskip=0pt
**
(even if, for some strange reason, the bibliography is being set with other
values, we want to have *\leftskip* and *\rightskip* be zero inside the
preliminary *\vbox*), and
also
**
\hbadness=10000 \hfuzz=\maxdimen
**
(so that *Underfull* and *Overfull* boxes will be reported only later, not
during the *\vbox* step), all followed by
**
\noindent
**
to preclude any extra indentation in our test *\vbox*.

But if we have an empty field (page~\ref{EFIELD}), in which case
our *\vbox* will have width ~*0pt*,
\footnote{The *\hsize=\maxdimen*
 within our *\vbox*\pagelabel{MAXD}
 simply describes the width of paragraphs
of text within the *\vbox*, not necessarily the width of the *\vbox* itself.}
 we want to reset
our box to *\box\voidb@x*.  We can do this with
**
\unskip\setbibinfo@#1\egroup
"9\def\aftergroup@{\ifdim\wd#1=0pt \setbox#1=\box\voidb@x\fi}"9
\setbox#1=\vbox\bgroup "9\aftergroup\aftergroup@"9 . . .
**
 Here the `*\aftergroup@*' is performed immediately after the
*\egroup* from the next field (or from *\endbib*)
that eventually matches the *\bgroup*. 

 In addition, in a few cases
we will need to add something extra right after the first *\egroup* (namely,
settings for the flags *\ifprevjour* and *\ifprevbook*).
 So
for this general case
we define
\C**
\def\Setnonemptybox@#1#2{%
 \unskip\setbibinfo@#1\egroup#2%
 \def\aftergroup@{\ifdim\wd#1=0pt
  \setbox#1=\box\voidb@x\fi}%
 \setbox#1=\vbox\bgroup \aftergroup\aftergroup@
  \hsize=\maxdimen \leftskip=0pt \rightskip=0pt
  \hbadness=10000 \hfuzz=\maxdimen
 \noindent}
**
 and then for the more common case we define
\C**
\def\setnonemptybox@#1{\Setnonemptybox@#1\relax}
**

\small Notice that we used *\noindent@* in the definition of *\bib*, but
*\noindent* in the definition of *\Setnonemptybox@*. That is because there
is a difference between the situation
\Litbox0=**
\bib \pagelabel{...} \no . . . \endbib
**
$$\box0\tag"\style{\bf A}"$$
where the invisible *\pagelabel* occurs before any field,
and something like
\Litbox0=**
\bib  . . .  \paper \pagelabel{...} . . . \endbib
**
$$\box0\tag"\style{\bf B}"$$
where the *\pagelabel* occurs within a field.

In case ({\bf A}), the *\bib* contributes a *\bgroup* (via the *\bib@*), and
the *\no* supplies the ending *\egroup*. Within this group, the
*\pagelabel{...}* has already deleted the final space, but even if it didn't,
the *\unskip* before the *\egroup* contributed by *\no* would get rid of it.
Consequently, nothing except a *\write* is contributed by this group. But if
we tried to be too careful, and replaced the *\bgroup* in *\bib@* with
**
\bgroup\futurelet\next\pretendspace@
**
then, since the invisible *\pagelabel* follows,
the results would be wrong: 
\list
\item First *\pretendspace* would contribute *\hskip-1pt\hskip1pt*.
\item Then the *\prevanish@* in *\pagelabel* would set *\saveskip@* to~ *1pt*
and remove the *\hskip1pt*.
\item Then the *\postvanish@* in *\pagelabel* would add back the *1pt* and
then delete the next space, if any.
\item Consequently, the *\unskip\egroup* in *\no* would remove the final
*1pt*, leaving an extra *\hskip-1pt* at the beginning.
\endlist

In case ({\bf B}), however, the *\noindent* (which eventually calls the
combination
*\futurelet\next\pretendspace@*) makes everything work out correctly if an
invisible element occurs first (followed by something else). Of course, this
won't work
if a *\pagelabel* appears within an {\it empty\/} field, but that doesn't
seem worth worrying about!	
\endsmall

\nopunct\section{\CS{no}, \CS{key}, \dots.}
Now we are ready to give definitions of *\no*, *\key*, \dots, many of 
which are 
quite
similar.  First we have
\C**
\def\no{\setnonemptybox@\nobox@}
\def\key{\setnonemptybox@\keybox@\bf}
\def\by{\setnonemptybox@\bybox@}
**
Notice that *\key* specifies *\bf* for the font.

For *\bysame* we simply specify the desired rule, rather than waiting for
user input:
\C**
\def\bysame{\setnonemptybox@\bybox@
 \leaders\hrule\hskip3em\null}
**
The *\null* is essential, to prevent the *\unskip* from the next field from
deleting this *\leaders* glue (compare the \lamstex~Manual, page~225).

The definition of *\paper* is a little more complicated, because we
have to begin with~*``* when *\ifpaperinquotes@* is true,
 except not
when *\noquotes* precedes *\paper*.  To find out this latter information,
 we use
**
\getbibinfo@\paperbox@
**
which will *\let\nextv@=1* if *\noquotes* preceded *\paper*, but
will\linebreak 
*\let\nextv@=0* otherwise:
\C**
\def\paper{\setnonemptybox@\paperbox@
 \ifpaperinquotes@
  \getbibinfo@\paperbox@
  \if\nextv@1\else``\fi
 \else
  \it
 \fi}
**
Notice that we've specified *\it* when *\ifpaperinquotes@* is false (even if
*\noquotes* preceded *\paper*).

The next definition reverts to the simple case,
\C**
\def\paperinfo{\setnonemptybox@\paperinfobox@}
**
but the definition of *\jour* uses *\Setnonemptybox@*, since we need to
set *\ifprevjour@* true (for possible use by *\morebib* later on):
\C**
\def\jour{\Setnonemptybox@\jourbox@\prevjour@true}
**

The next definitions are simple (*\vol* merely adds *\bf* for the font),
\C**
\def\vol{\setnonemptybox@\volbox@\bf}
\def\issue{\setnonemptybox@\issuebox@}
\def\yr{\setnonemptybox@\yrbox@}
**

But *\toappear* is handled quite specially:
\C**
\def\toappear{\noprepunct\finalinfo(to appear)}
**


Then come another two simple definitions:
\C**
\def\pg{\setnonemptybox@\pgbox@}
\def\pp{\setnonemptybox@\ppbox@}
**

The definition of *\book* has both the complexities of
*\paper* (involving quotation marks) and *\jour* (setting a flag),
\C**
\def\book{\Setnonemptybox@\bookbox@\prevbook@true
 \ifbookinquotes@\getbibinfo@\bookbox@
  \if\nextv@1\else``\fi
 \else
 \it
\fi}
**
and the definition of *\inbook* has yet another clause, because of the
flag *\ifinbook@*:
\C**
\def\inbook{\Setnonemptybox@\inbookbox@\prevbook@true
 \ifininbook@ in \fi
 \ifbookinquotes@\getbibinfo@\inbookbox@
  \if\nextv@1\else``\fi
 \fi}
**
(In this case we don't change fonts even if there are no
quotation marks.)

Then comes another bunch of simple definitions,
\C**
\def\bookinfo{\setnonemptybox@\bookinfobox@}
\def\publ{\setnonemptybox@\publbox@}
\def\publaddr{\setnonemptybox@\publaddrbox@}
\def\ed{\setnonemptybox@\edbox@}
\def\eds{\setnonemptybox@\edsbox@}
\def\lang{\setnonemptybox@\langbox@}
\def\finalinfo{\setnonemptybox@\finalinfobox@}
**

This leaves only *\transl*, *\morebib*, and *\anotherbib*, all of which
are treated somewhat similarly---it will be easiest to understand their
definitions later (section~\Sref{ENDS})
after examining how *\endbib* puts all the information together.


\section{Manipulating the \CS{vbox}'es\label{VBOXI}}
At the end of a *\bib...\endbib* entry,
we will have stored all our information in various *\vbox*'es, and we now
have to get information out of each such  box, *#1*, with a construction
*\getbox@#1*.  Most of the time we could simply use
**
\def\getbox@#1{\setbox0=\vbox{\unvbox#1
 \setbox0=\lastbox
 \global\setbox1=\hbox{\unhbox0 \unskip\unskip\unpenalty}}
 \unhbox1 }
**
Here the inner *\box0* (*\lastbox*) is the final line of this
one line paragraph (having *\hsize=\maxdimen*), at the end of which we have
(see {\it The \tex book}, page~100),
\setbox0\hbox{\<}\setbox1\hbox{\>}
**
\penalty 10000 "copy0\parfillskip glue"copy1 "copy0\rightskip glue"copy1
**
which we delete with the *\unskip\unskip\unpenalty*.

But since line breaking commands may have
occurred (either in the middle of the field, or at the end),
 our *\vbox* may have several *\hbox*'es, separated by glue and
possibly penalties (*\clubpenalty*, etc.), and we may have to use a *\loop*
to discover all these boxes.
We
 add *\vskip-10000 pt* at the beginning as a
marker, the assumption that such a *\vskip* won't be
inserted otherwise.
\C**
\def\getbox@#1{\setbox0=\vbox{\vskip-10000pt "8VSMARK"8
 \unvbox#1%   "8GUNV"8
"2
 \setbox0=\lastbox
"2
 \global\setbox1=\hbox{\unhbox0 \unskip\unskip\unpenalty}
"2
 \ifdim\lastskip=-10000pt 
 \else
"2
  \loop
   \ifdim\lastskip=-10000 pt
"2
   \else
    \unskip\unpenalty\setbox0=\lastbox
    \global\setbox1=\hbox{\unhbox0 \unhbox1}%
   \repeat
"2
 \fi}%
 \unhbox1 }
**
Notice that we use the test *\ifdim\lastskip=-10000pt* before entering
the *\loop*, even though it is also used within the *\loop*; this 
allows us to bypass the *\loop* completely if it is unnecessary.


\small The combination *\setbox0=\lastbox* occurs rather often, so right
before the definition of *\getbox@* we have
\C**
\def\setboxzl@{\setbox\z@\lastbox}
**
and then we use *\setboxzl@* throughout.  However, for the sake of
readability, we will always simply print `*\setbox0=\lastbox*'.
\endsmall

\section{Line breaking commands\label{BIBMACS}}
Next we have to deal with the problem of a line breaking command appearing at
the end of one our fields, since the appropriate penalties must be
inserted {\it after\/} the punctuation that is normally added after the
field. These line breaking commands
 produce 
\setbox0\hbox{\it n}
**
\null\kern-"copy0",sp",\kern","copy0",sp
**
at the end of the horizontal list produced by *\getbox@*.
More specifically, 
\list \advance\litindent15pt
\item *\nolinebreak* produces
\setbox0\hbox{\<possible glue\>}
**
\penalty10000 "box0 \null\kern-1sp\kern1sp
**
The \<possible glue\> comes about because *\nolinebreak* remembers the
glue before it, and inserts it after the *\penalty10000*, so that this
glue does {\it not\/} disappear.  Of course, it is unlikely that any one would
want to have such a non-disappearing space at the end of a field, but we
might as well allow for the possibility.
\item Similarly, *\allowlinebreak* produces
\setbox0\hbox{\<possible glue\>}
**
\penalty0 "box0 \null\kern-1sp\kern1sp
**
\item *\linebreak* produces
\setbox0\hbox{\<}\setbox1\hbox{\>}
**
\penalty-10000 "copy0"relax0pt glue"copy1 \null\kern-1sp\kern1sp
**
Here the *\null\kern-1sp\kern1sp* comes from the last *\hbox* in the
*\vbox*, while the *\penalty-10000 "copy0"relax0pt glue"copy1* comes from the
previous *\hbox*, the *"copy0"relax0pt glue"copy1*
 being the *\rightskip* glue, and the
*\penalty-10000* the penalty from *\linebreak*.
\item *\newline* produces
\setbox0\hbox{\<}\setbox1\hbox{\>}
**
"hskip-20pt\null \hfil \penalty-10000 "copy0"relax0pt"copy1 \null\kern-2sp\kern2sp
**
Now the *\null\hfil\penalty-10000 "copy0"relax0pt glue"copy1* comes from the next to last
*\hbox*, the *"copy0"relax0pt glue"copy1*
 again being the *\rightskip* glue, and the
*\null\hfil\penalty-10000* coming from the *\newline*.
\endlist

 Since such  small
*\kern*'s were
presumably not inserted by the user, their presence indicates that one of
the line breaking commands occurred; the value of the *\kern*, 
together with the *\penalty* before the *\null*, allows us to
distinguish the four cases.

We introduce
the routine *\adjustpunct@#1*, where *#1* is normally some punctuation
symbol, which will find such information, delete all the *\kern*'s,
*\penalty*'s, etc., add the punctuation *#1*, and then put back
the proper *\penalty*.
   We begin with
**
\def\adjustpunct@#1{\count@=\lastkern
**
so that *\count@* is the number of scaled points in *\lastkern*. This will
normally either be ~*0*, because there is no *\kern*, or if a *\kern* was
inserted by the user, it will be
something reasonably large or large negative,
presumably \hbox{*>2*} or \hbox{*<-2*}. 
In such cases, we just want to add the punctuation
*#1*, except that this must be followed by *\closequotes@*, in case
*''* needs to be added after the punctuation, because the previous field began
with~*``*:
**
\def\adjustpunct@#1{\count@=\lastkern
 \ifnum\count@=0 #1\closequotes@\else
 \ifnum\count@>2 #1\closequotes@\else
 \ifnum\count@<-2 #1\closequotes@\else
  . . .
**

In the remaining, more interesting case, we use
**
\unkern\unkern\setbox0=\lastbox
**
to get rid of the
\setbox0\hbox{\it n}
**
\null \kern-"copy0",sp\kern","copy0",sp
**
Then we save the previous glue in *\skip@* and remove it:
**
\skip@=\lastskip \unskip
**
Now we've reached the point where the original *\penalty* is revealed;
we store it in *\count@@* and remove it:
**
\count@@=\lastpenalty \unpenalty
**
Moreover, in the case of *\newline* (*\count@* is~*2*), we also get rid of
the *\null\hfil*:
**
\ifnum\count@=2 \unskip \setbox0=\lastbox \fi
**
Now we can add the punctuation *#1*, followed by *\closequotes@*;
if *\skip@* is non-zero, because of the \<possible glue\> in the case of
*\nolinebreak* or *\allowlinebreak*, we add this first:
**
\ifdim\skip@=0pt \else \hskip\skip@ \fi
#1\closequotes@
**
In the case of *\newline* we then add back a *\null\hfill*, and in all
cases we add back the original *\penalty*, now stored in *\count@@*:
\C**
\def\adjustpunct@#1{\count@=\lastkern
 \ifnum\count@=0 #1\closequotes@\else
 \ifnum\count@>2 #1\closequotes@\else
 \ifnum\count@<-2 #1\closequotes@\else
  \unkern\unkern\setbox0=\lastbox
  \skip@=\lastskip \unskip
  \count@@=\lastpenalty\unpenalty
  \ifnum\count@=2 \unskip\setbox0=\lastbox\fi
  \ifdim\skip@=0pt \else \hskip\skip@ \fi
  #1\closequotes@
  \ifnum\count@=2 \null\hfill\fi
  \penalty\count@@
 \fi\fi\fi}
**

\section{Adding punctuation before a field\label{VBOXII}}
The routine *\adjustpunct@* figures prominently in the routine
**
\prepunct@#1#2
**
which adds *#1*,
 some sort of 
punctuation, before the field corresponding to *#2*,
which  is *\paperbox@*, \dots.

Before we consider this routine, we need to reconsider the information
in *\bibinfo@*, which we use with the
routine *\getbibinfo@* to funnel  information from *\bibinfo@* into
*\next@*, \dots, *\nextv@*.
Note that the information derived from the value of *\next@* and *\nextii@*,
i.e., whether or not *\nopunct* or *\nospace* preceded the field, is not
used when printing the field; this information has to be used
by the {\it next\/} field, to decide whether to print the finishing
punctuation and space, before printing the new material from that next field.
 Consequently,
the information from the value of *\next@* and *\nextii@* has to be passed
along to the next field.  We will pass this information along by setting the
values of the flags *\ifnopunct@* and *\ifnospace@* once again, thus
providing them with a dual role.


Now our definition of *\prepunct@* begins
**
\def\prepucnt@#1#2{\getbibinfo@#2%
 "hskip-10pt% first part
 \ifnopunct@
 \else
  \if\nextiii@0\adjustpunct@#1\fi
 \fi
"2
 \closequotes@
 \ifnospace@
 \else
  \if\nextiv@0\space\else\fi
 \fi
 "hskip-10pt% second part
 \nopunct@false \nospace@false
 \if\next@1\nopunct@true\fi
 \if\nextii@1\nospace@true\fi
**

Before examining the first part of this code, consider the second part:
this sets *\ifnopunct@* to be true if *\nopunct@* preceded the field
and *\ifnospace@* to be true if *\nospace@* preceded the field.

The first part of the code should now make more sense, when we
remember that
 those same assignments will have been made by the field which precedes
this field: 
The test *\ifnopunct@* is true if
 the previous field is not supposed to have punctuation at the end, 
and *\nextiii@* will be~*1* (rather than *0*) if the current field
was followed by *\noprepunct*.  In either of these cases,
 we don't supply any punctuation; otherwise, we use *\adjustpunct@#1*
to supply the punctuation *#1*. Even when no punctuation is supplied, we
need *\closequotes@*, in case
the previous field set *\ifopenquotes@* true (if *\adjustpunct@* {\it was\/}
used, the *\closequotes* within it has already set *\ifopenquotes@* to be
false [page~\ref{OQFALSE}], so we won't be adding closing quotes twice).
Space following 
the punctuation is handled similarly, using the flags *\ifnospace@* and
the value of *\nextiv@*.
\C**
\def\prepunct@#1#2{\getbibinfo@#2%
 \ifnopunct@
"2
 \else
   \if\nextiii@0\adjustpunct@#1\fi
 \fi
"2
 \closequotes@
"2
 \ifnospace@
 \else
  \if\nextiv@0\space\else\fi
 \fi
"2
 \nopunct@false\nospace@false
 \if\next@1\nopunct@true\fi
 \if\nextii@1\nospace@true\fi}
**

 *\prepunct@#1#2* is usually followed immediately by *\getbox@#2*, so
we introduce an abbreviation for that combination:
\C**
\def\ppunbox@#1{\prepunct@{#1}#2\getbox@#2}
**

\section{\CS{endbib\@}\label{SEMICOL}}
 Now we're ready to actually typeset all the
information acquired by a *\bib...\endbib* entry.
First we 
\C**
\let\semicolon@=;
**
so that we can use *\semicolon@* in place of *;* everywhere.  This is done
solely for the benefit of French styles (compare section~\Sref{ALF}), 
which can then redefine *\semicolon@* (presumably as something like
*" ;*).


The final command *\endbib* is defined in terms of
*\endbib@*, which does most of the work.
We begin with
**
\def\endbib@{%
 \ifbeginbib@
  \ifvoid\nobox@
   \ifvoid\keybox@\else
    \hbox to\bibindent@{[\getbox@\keybox@]\hss}\fi
  \else
   \hbox to\bibindent@{\hss\getbox@\nobox@. }
  \fi
 . . .
**
Thus, when *\ifbeginbib@* is true
 (which will  usually be the case, unless we
are printing remaining information from *\morebib*, *\anotherbib*, or
*\transl*),
if *\box\nobox@* isn't void we
start our *\noindent@*'ed paragraph with 
**
\hbox to\bibindent@{\hss\getbox@\nobox@. }
**
a box of width *\bibindent@*, which is also the amount of hanging indentation
we will be using,
containing 
 the
information in *\box\nobox@*. This information
(from *\getbox@\nobox@*) is followed by a period
and a space, and preceded by *\hss* (rather than *\hfil*, just in case the
number is too long). 
Because the *\ifvoid* test always tells us whether or not a particular field
has been set, we don't need any flags for this.  Note also that *\getbox@#1*
uses *\unvbox#1* (page~\ref{GUNV}),
 so that once we print the information for a
field, the box containing that information
has become void again.


If *\box\nobox@* is void,  we instead use
the information in *\box\keybox@*, if that isn't void.  In this case
we surround the information with brackets, and have it start at the left
margin, with the additional space at the right.

In the other case, where *\ifbeginbib@* is false, we use
**
\else
 \nopunct@true  "8NOPUNCTT"8
 \ifvoid\bybox@\else\getbox@\bybox@\fi
\fi
**
We first set *\ifnopunct@* to be true because we don't want the first
field of our *\morebib* or *\anotherbib* or *\transl* portion to
add any punctuation to the end of the previous field, which 
will already have been supplied with a closing~ *;* (see 
page~\ref{FINTCH}ff.). Normally
*\box\bybox@* will be void for this subsequent portion, but 
*\by* could conceivably be used after *\anotherbib*, so we add that in.


After this preamble, we start to add the other
various elements in the required
order. Although  *\transl* isn't defined until section~\Sref{ENDS}, it
does end up storing its information in *\box\translbox@*, just like
other fields; if this box is nonvoid, then we must be setting this
second portion of the entry, and this information should come first, so
 we now add
**
\ifvoid\translbox@\else\ppunbox@,\translbox@\fi
**
to print the information.

Next comes
**
\ifvoid\paperbox@
\else
 \ppunbox@,\paperbox@
 \ifpaperinquotes@
  \if\nextv@1\else\openquotes@true\fi
 \fi
\fi 
**
Thus, if *\box\paperbox@* isn't void we add the information in it, 
with appropriate punctuation and spacing before it.  The *\ppunbox@* routine
has already used *\getbibinfo@\paperbox@* to get information from
*\bibinfo@*. When the flag *\ifpaperinquotes@* is true (so that we are
enclosing paper titles in quotation marks), then the paper title normally
has begun with *``* and we want to set *\ifopenquotes@* to be true, so that
the next routine will know the add the *''*; however, we don't do this
when the *\bibinfo@* has caused
*\nextv@* to be~*1*, since this indicates that a *\noquotes* preceded the
*\paper*, in which case the opening *``* will not have been included in
the paper title.

After the paper title, we add any *\paperinfo*:
**
\ifvoid\paperinfobox@\else\ppunbox@,\paperinfobox@\fi
**

Then comes the information in *\jourbox@*, *\volbox@*, *\issuebox@*, \dots.
Information from *\volbox@*, \dots, should be added only if there was
\list\newnumstyle\list1\alph
\item information in *\jourbox@*;
\item or in the case of *\morebib*, information in a previous *\jourbox*.
\endlist
In the latter case, *\ifprevjour@* will have been set true, so we use
\setbox0\hbox{\<material for *\vol*, *\issue*, *\yr*, *\pp*, *\pg*\>}
**
\test@false
\ifvoid\jourbox@\else\test@true\ppunbox@,\jourbox@\fi
\ifprevjour@\test@true\fi
\iftest@
 "box0
\fi
**

For *\volbox@* we use
**
\ifvoid\volbox@\else\ppunbox@\relax\volbox@\fi
**
since there is no punctuation before the information in *\volbox@*.
Similarly, 
**
\ifvoid\issuebox@
 \else\prepunct@\relax\issuebox@ no.~\getbox@\issuebox@\fi
"2
\ifvoid\yrbox@\else\prepunct@\relax\yrbox@
 (\getbox@\yrbox@)\fi
"2
\ifvoid\ppbox@\else\ppunbox@,\ppbox@\fi
"2
\ifvoid\pgbox@\else\prepunct@,\pgbox@
  p.~\getbox@\pgbox@\fi
**
puts ``no. '' before the *\issue*, which has no punctuation before it,
encloses the *\yr* in parentheses, with no punctuation before it, and
 adds ``p.~'' before *\pg*.

Next comes information for a book. As with *\jour*, succeeding information
will be printed only if there is a *\book* or *\inbook* or when 
*\ifprevbook@*
is true. The flag *\ifbookinquotes@* also requires steps similar to those
used for *\paper*:
\setbox0\hbox{\<subsidiary fields for *\book*\>}
**
\test@false
\ifvoid\bookbox@\else
 \test@true\ppunbox@,\bookbox@
 \ifbookinquotes@\if\nextv@1\else\openquotes@true\fi\fi
\fi
\ifvoid\inbookbox@\else
 \test@true\ppunbox@,\inbookbox@
 \ifbookinquotes@\if\nextv@1\else\openquotes@true\fi\fi
\fi
\ifprevbook@\test@true\fi
\iftest@
 "copy0
\fi
**

 The subsidiary fields include *\edbox@*, *\edsbox@*,
*\bookinfobox@*,\linebreak 
*\publbox@*, *\publaddrbox@*, and once again *\yrbox@*, *\ppbox@*
and\linebreak 
 *\pgbox@*,
since the latter three can be  with *\paper* as well as with *\book*.
There's nothing here that we haven't already considered:
**
\ifvoid\edbox@\else\prepunct@\relax\edbox@
  (\getbox@\edbox@, ed.)\fi
"2
\ifvoid\edsbox@\else\prepunct@\relax\edsbox@
  (\getbox@\edsbox@, eds.)\fi
"2
\ifvoid\bookinfobox@\else\ppunbox@,\bookinfobox@\fi
"2
\ifvoid\publbox@\else\ppunbox@,\publbox@\fi
"2
\ifvoid\publaddrbox@\else\ppunbox@,\publaddrbox@\fi
"2
\ifvoid\yrbox@\else\ppunbox@,\yrbox@\fi
"2
\ifvoid\ppbox@\else\prepunct@,\ppbox@
  pp.~\getbox@\ppbox@\fi
"2
\ifvoid\pgbox@\else\prepunct@,\pgbox@
  p.~\getbox@\pgbox@\fi 
**

Then come the finishing touches.  At this point the flag
*\ifendbib@* will be important.  It will have been set true if we
are finishing off the whole *\bib...\endbib* entry, but it will be false
if we are simply printing the first portion of an entry, with a further 
portion from *\morebib* or *\anotherbib* or *\transl* to follow.
The possibility of a *\finalinfo* field will also play a role. We begin
with the case where there was no *\finalinfo* field:
**
\ifvoid\finalinfobox@
 \ifendbib@
  \ifnopunct@\else.\closequotes@\fi
 \else
  \ifvoid\langbox@\else\space(\getbox@\langbox@)\fi
  \/\semicolon@\closequotes@  "8FINTCH"8
. . .
**
In other words, if we are truly at the end, we print a period, unless
a *\nopunct* preceded the previous field, which will be indicated by
*\ifnopunct@* being true; the *\closequotes@* is added just in case
the previous field happened to be a *\jour* or *\book* in quotes.

  Otherwise (*\morebib* or *\anotherbib* or
*\transl* information follows), we add any *\lang* field information in
parentheses, and then a semicolon (with the italic correction *\/*
before it, in case the previous field was set in a slanted font),
 again calling on *\closequotes@*
to supply any necessary closing quotes.
Notice that no space has been added after the semicolon. The *\prepunct@*
or *\ppunbox* for the next field will add in that space, even though
the extra punctuation will not be added (because we set *\ifnopunct@*
to be true when *\ifbeginbib@* is false [page~\ref{NOPUNCTT}]).



For the other case, where there is a *\finalinfo* field, we use
**
\else
 \ifendbib@
  \ppunbox@{.\spacefactor3000\relax}\finalinfobox@
   \ifnopunct@\else.\fi
  \else
  \ppunbox@,\finalinfobox@\/\semicolon@\fi
 \fi
**
So, if we are at the very end, we add a period before the *\finalinfo*
field (unless a *\nopunct* or *\noprepunct* tells us not to), and
then a final period (unless a *\nopunct* preceded the *\finalinfo*). 
After the period before the *\finalinfo* material we
change the *\spacefactor* to *3000*,
since that period
is not an abbreviation.
  If we're not at the very end, so that the *\finalinfo*
applies only to the first portion of the entry, then we want a comma
before this information, and a semicolon (with *\/* before it).


Finally, we add
**
\ifvoid\langbox@\else\space(\getbox@\langbox@)\fi
**
at the very end, to take care of a *\lang* field that has to go after
everything else.

Our whole definition thus reads:
\C**
\def\endbib@{%
 \ifbeginbib@
"2
  \ifvoid\nobox@
   \ifvoid\keybox@\else
    \hbox to\bibindent@{[\getbox@\keybox@]\hss}\fi
"2
  \else
   \hbox to\bibindent@{\hss\getbox@\nobox@. }\fi
  \ifvoid\bybox@\else\getbox@\bybox@\fi
"2
 \else
  \nopunct@true
  \ifvoid\bybox@\else\ppunbox@\relax\bybox@\fi
 \fi
"2
 \ifvoid\translbox@\else\ppunbox@,\translbox@\fi
"2
 \ifvoid\paperbox@\else\ppunbox@,\paperbox@\ifpaperinquotes@
  \if\nextv@1\else\openquotes@true\fi\fi\fi
"2
 \ifvoid\paperinfobox@\else\ppunbox@,\paperinfobox@\fi
"2
 \test@false
 \ifvoid\jourbox@\else\test@true\ppunbox@,\jourbox@\fi
 \ifprevjour@\test@true\fi
"2
 \iftest@
"2
  \ifvoid\volbox@\else\ppunbox@\relax\volbox@\fi
"2  
  \ifvoid\issuebox@
   \else\prepunct@\relax\issuebox@ no.~\getbox@\issuebox@\fi
"2
  \ifvoid\yrbox@\else\prepunct@\relax\yrbox@
    (\getbox@\yrbox@)\fi
"2
  \ifvoid\ppbox@\else\ppunbox@,\ppbox@\fi
"2
  \ifvoid\pgbox@\else\prepucnt@,\pgbox@ p.~\getbox@\pgbox@\fi
 \fi
"2
 \test@false
 \ifvoid\bookbox@\else\test@true\ppunbox@,\bookbox@
  \ifbookinquotes@\if\nextv@1\else\openquotes@true\fi\fi
 \fi
"2
 \ifvoid\inbookbox@\else\test@true\ppunbox@,\inbookbox@
  \ifbookinquotes@\if\nextv@1\else\openquotes@true\fi\fi
 \fi
"2
 \ifprevbook@\test@true\fi
"2
 \iftest@
"2
  \ifvoid\edbox@\else\prepunct@\relax\edbox@
   (\getbox@\edbox@, ed.)\fi
"2
  \ifvoid\edsbox@\else\prepunct@\relax\edsbox@
   (\getbox@\edsbox@, eds.)\fi
"2
  \ifvoid\bookinfobox@\else\ppunbox@,\bookinfobox@\fi
"2
  \ifvoid\publbox@\else\ppunbox@,\publbox@\fi
"2
  \ifvoid\publaddrbox@\else\ppunbox@,\publaddrbox@\fi
  \ifvoid\yrbox@\else\ppunbox@,\yrbox@\fi
"2
  \ifvoid\ppbox@\else\prepunct@,\ppbox@ pp.~\getbox@\ppbox@\fi
"2
  \ifvoid\pgbox@\else\prepunct@,\pgbox@ p.~\getbox@\pgbox@\fi 
 \fi
"2
 \ifvoid\finalinfobox@ 
"2
  \ifendbib@
   \ifnopunct@\else.\closequotes@\fi
"2
  \else
   \ifvoid\langbox@\else\space(\getbox@\langbox@)\fi
   \semicolon@\closequotes@
  \fi
"2
 \else
"2
  \ifendbib@
   \ppunbox@{.\spacefactor3000\relax}\finalinfobox@
    \ifnopunct@\else.\fi
"2
  \else
   \ppunbox@,\finalinfobox@\semicolon@\space\fi
 \fi
 \ifvoid\langbox@\else\space(\getbox@\langbox@)\fi
}
**



\section{\CS{endbib}, \CS{morebib}, \CS{anotherbib}, and \CS{transl}\label
 {ENDS}}
 The construction *\endbib*  begins with 
**
\unskip\egroup
**
just like all other fields, and then it calls *\endbib@* with the
flag
*\ifendbib@* set true (*\ifbeginbib@* has already been set true
by *\bib*),
finishing up with a *\par* and then an
*\endgroup* to match the *\begingroup* supplied by the original *\bib*:
\C**
\def\endbib{\unskip\egroup
 \endbib@true\endbib@\par\endgroup}
**

*\morebib* uses an *\endbib@* to set the material so far, just like *\endbib*,
except that we set *\ifendbib@* 
to be false:
**
\def\morebib{\unskip\egroup
 \endbib@false\endbib@
**
And then we want to call *\bib@* again, to deal with the following material,
except that we also need to reset *\bibinfo@* to be empty
 and *\ifbeginbib@* to be false:
\C**
\def\morebib{\unskip\egroup
 \endbib@false\endbib@
 \global\let\bibinfo@=\empty
 \beginbib@false
 \bib@}
**

And *\anotherbib* is almost the same, except that we also
set *\ifprevjour@*
and *\ifprevbook@* to be false before the *\bib@*,
 so that no previous material will be
``remembered'': 
\C**
\def\anotherbib{\unskip\egroup
 \endbib@false\endbib@
 \global\let\bibinfo@=\empty
 \beginbib@false
 \prevjour@false\prevbook@false
 \bib@}
**

Finally, *\transl* is something like a cross between *\morebib* and
a more standard field. We want to begin with something like
**
\unskip\egroup
\endbib@false\endbib@
**
in order to print the previous information. 

Then we want to call *\bib@* again, after first  setting
*\ifbeginbib@* to be false, as with *\morebib*. Now we start with
**
\beginbib@false
\bib@
\egroup
\def\aftergroup@{...}
\egroup\setbox\translbox@=\vbox\bgroup
 \aftergroup\aftergroup@ \hsize=\maxdimen . . .
 \noindent@}
**
so that we will be putting the following field into *\box\translbox@* in
essentially the same way that *\paper*, *\jour*, etc., put their fields
into boxes, using *\setnonemptybox@*.  The one thing we are missing from
*\setnonemptybox@* is the procedure for storing information about
any *\nopunct*, \dots, *\noquotes* that precedes the *\transl*. This
information should be stored in *\bibinfo@*, except that any other information
in *\bibinfo@* should be emptied out, ready to be refilled, if necessary,
with current information for the fields following *\transl*.  

To do this, we first store the information in *\translinfo@*, before the
*\egroup*,
**
\def\transl{\unskip
 \xdef\translinfo@{\the\translbox@,\ifnopunct@1\else0\fi
  \ifnospace@1\else0\fi\ifnoprepunct@1\else0\fi
  \ifnoprespace@1\else0\fi0}
**
(we simply use *0* as the last value,
 without bothering about the value of *\ifnoquotes@*, since the
value is never used in setting the translation information anyway),
and
then we set *\bibinfo@* to be *\translinfo@* before calling *\bib@*:
\C**
\def\transl{\unskip
 \xdef\translinfo@{\the\translbox@,\ifnopunct@1\else0\fi
  \ifnospace@1\else0\fi\ifnoprepunct@1\else0\fi
  \ifnoprespace@1\else0\fi0}%
"2
 \egroup
 \endbib@false
 \endbib@
"2
 \global\let\bibinfo@=\translinfo@
 \beginbib@false
 \bib@
"2
 \egroup
"2
 \def\aftergroup@{\ifdim\wd\translbox@=0 
  \setbox\translbox@=\box\voidb@x\fi}%
"2
 \setbox\translbox@=\vbox\bgroup
  \aftergroup\aftergroup@
  \hsize=\maxdimen \leftskip=0pt \rightskip=0pt
  \hbadness=10000 \hfuzz=\maxdimen
  \noindent@}
**
\medskip

And that jolly well finishes off the bibliography macros!




\chapterg Interfacing with B{\eightbf IB}\kern-.1em\tex
 \label{bibtex}\endchapterg
\runningchapter{Interfacing with B{\eightit IB}\kern-.1em\tex}


It turns out that we can easily prepare an *.aux* file on which \bibtex\ can
operate, so that a \lamstex\ file can use the resulting *.bbl* file.
The control sequence 
**
\UseBibTeX
**
will set things up for this.
When *\UseBibTex* is specified (preferably close to the beginning of the
document), a
**
\bibliographystyle{...}
**
line  should also appear somewhere. 

Furthermore, when *\UseBibTeX* is specified,
 *\cite* will essentially function just as in \latex@, rather
than as in the previous chapter, except that we will 
continue to use *(...)* for an optional argument rather than *[...]*.
As in \latex@, a citation of the form
\setbox0\hbox{\<key\>$_{\text{1}}$}
\setbox1\hbox{\<key\>$_{\text{2}}$}
**
\cite{"box0,"box1,...}
**
had better not 
have  spaces after the commas, because this multiple argument is going to be
passed directly to the *.aux* file, on which \bibtex\ operates, and \bibtex\
will insist that no space appears. (Of course, spaces will be made to appear 
after the commas in the output.)


Finally, when *\UseBibTeX* is specified,
instead of a
**
\makebib
 . . .
\endmakebib
**
region, a line
\setbox0\hbox{\<source list\>$_{\text{1}}$}
\setbox1\hbox{\<source list\>$_{\text{2}}$}
**
\bibliography{"box0,"box1,...}
**
should appear, at the appropriate place. 
In this case,
 no specific references should be
given, either in \latex\ or in \lamstex\ format. The references will be
supplied by the *.bbl* file that will eventually be made, and which the
*\bibliography* command will read in,
and
any additions
or changes would be made directly in that file. 


\section{\CS{UseBibTeX}}
We first declare new streams for writing the *.aux* file, and reading
the *.bbl* file:
\C**
\newwrite\auxwrite@
\newread\bbl@
**

Now *\UseBibTeX*
must first open up an *.aux* file,
**
\immediate\openout\auxwrite@=\jobname.aux
**
and then redefine *\cite*.  
We will simply
**
\let\cite=\BTcite@
**
where *\BTcite@* is defined separately afterwards. 
That allows a style file to redefine  aspects of *\BTcite@* that deal with
the material actually printed.


*\UseBibTeX* will also define *\nocite*,
**
\def\nocite#1{\immediate\write\auxwrite@{\string\citation{#1}}
**
and *\bibliographystyle*,
**
\def\bibliographystyle#1{\immediate\write\auxwrite@
  {\string\bibstyle{#1}}}
**

Finally, it must define *\bibliography*, and this is somewhat more complex.
To begin with, we want to
**
\def\bibliography@W{Bibliography}
**
so that *\newword\bibliography* can be used.
Then we start with
**
\def\bibliography#1{\immediate\write\auxwrite@
  {\string\bibdata{#1}}
 . . .
**
Then we have to see whether a *.bbl* file exists.  If it doesn't, we simply
give a message to that effect,
but if the *.bbl* file does exists, we read in a special
macro file *bibtex.tex* before we *\input* the *.bbl* file, since
the *bibtex.tex* macros will make this a file that we can process,
**
\def\bibliography#1{\immediate\write\auxwrite@
  {\string\bibdata{#1}}%
 \immediate\openin\bbl@=\jobname.bbl
"2
 \ifeof\bbl@
  \W@{No .bbl file}%
"2
 \else
  \immediate\closein\bbl@
  \begingroup
  \input bibtex 
  \input\jobname.bbl 
  \endgroup
  \fi}
"2
**
Putting this all together, we have
\C** 
\def\UseBibTeX{\immediate\openout\auxwrite@=\jobname.aux 
"2
 \let\cite=\BTcite@
"2
 \def\nocite##1{\immediate\write\auxwrite@
   {\noexpand\citation{##1}}}%
"2
 \def\bibliographystyle##1{\immediate\write\auxwrite@
  {\string\bibstyle{##1}}}%
"2
 \def\bibliography@W{Bibliography}%
 \def\bibliography##1{%
  \immediate\write\auxwrite@{\string\bibdata{##1}}%
  \immediate\openin\bbl@=\jobname.bbl
"2
  \ifeof\bbl@
   \W@{No .bbl file}%
"2
  \else
   \immediate\closein\bbl@
   \begingroup    "8UBTBG"8
   \input bibtex 
   \input\jobname.bbl 
   \endgroup
  \fi}%
 }
**
We use *\string*'s rather than *\noexpand*'s (section
~\Sref{SACN})
so that
no extra
spaces will appear in the *.aux* file, since \bibtex\
doesn't seem to like that!


The definition of *\BTcite@* (compare the definition of *\cite* in the
previous chapter) leaves the parsing for commas to
*\BTcite@@"allowbreak..."allowbreak\BTcite@@*: 
\C**
\def\BTcite@{%
 \def\nextii@(##1)##2{%
  {\rm[}\BTcite@@##2,\BTcite@@{\rm," }{##1\/}{\rm]}%
  \immediate\write\auxwrite@{\string\citation{##2}}}%
 \def\nextiii@##1{{\rm[}\BTcite@@##1,\BTcite@@\/{\rm]}%
  \immediate\write\auxwrite@{\string\citation{##1}}}%
 \def\next@{\ifx\next(\expandafter\nextii@
  \else\expandafter\nextiii@\fi}%
 \futurelet\next\next@}%
**
Notice that *\nextii@*, used
in the case of an optional argument *(...)*, explicitly inserts a comma and
space (in the *\rm* font---see the small print note on page~\ref{RMCOMMA}).
 *\BTcite@@...,\BTcite@@*
 will be defined so that the comma and space is {\it
not\/} added after the final part of the argument.

The definition  of *\BTcite@@*
uses standard parsing methods.
For each individual `\<key\>*,*' combination in the argument `*#1,*'
we will call\linebreak
 *\BTcite@@@{*\<key\>*}* followed by `*{\rm," }*',
{\it except for the last such\/} \<key\>, where the comma will simply 
be dropped:
\C**
\def\BTcite@@#1,{\BTcite@@@{#1}\futurelet\next\BTcite@@@@}
\def\BTcite@@@@{\ifx\next\BTcite@@
 \expandafter\eat@\else{\rm, }\expandafter\BTcite@@\fi} 
**

Here
*\BTcite@@@* will  basically be equivalent to
*\ref*
 (compare the definition on page~\ref{DEFREF2}):
\C**
\catcode`\~=11
\def\BTcite@@@#1{\nolabel@\cite{#1}\relax
 \def\nextii@##1~##2\nextii@{##1}%
 \csL@{#1}\expandafter\nextii@\Next@\nextii@\fi}
\catcode`\~=\active
**

 The *\nolabel@\cite{#1}\relax*
 means that we will initially get an
error message or warning message
\setbox0\hbox{\<key\>}
**
No \label found for "box0.
**
which is reasonable, since a *\cite* is essentially like a *\ref*;
the label will be created when we have a *\bibitem* from the *.bbl* file.
As in \latex@, three passes will normally be required:
\list
\item First each *\cite* creates a *\citation* line in the *.aux* file.
\item Then \bibtex\ creates a *.bbl* file, with a *\bibitem* for
each key cited. When we \tex\ the file again, the *\bibitem*'s in the *.bbl*
file will be treated like *\label*'s, and write appropriate
information (forward references)
to the *.lax* file.
\item When we \tex\ the file yet again, these references will finally
be inserted.
\endlist


\small Because \bibtex\ makes \pagelabel{RMCOMMA}
 *\cite{...}* work like  *\ref{...}*, it is then not permissible
to say things like \pagelabel{OPARGCITE}
**
\cite{\bf ...}
**
Once can  type
\setbox0\hbox{\<key\>$_{\text{1}}$}
\setbox1\hbox{\<key\>$_{\text{2}}$}
**
By {\bf\cite{"box0,"box1}} we have ...
**
to print something like \medskip
\centerline{By [{\bf3}, {\bf4}] we have \dots{}}
\medskip
\noindent
(*\rm* has been explicitly specified for
the brackets and comma 
definitions), but
a change to the style file should be used if all citations are
supposed to be in *\bf*. 
It is even possible to type something like
\setbox0\hbox{\<key\>}
**
By {\bf\cite(\it page~123){"box0}} we have ...
**
to print something like \medskip
\centerline{By [{\bf3}, {\it page~123\/}] we have \dots{}}
\medskip
\noindent
(there are no restrictions on the material occurring in the
optional argument).  In the 
definition of *\BTcite@* we typed *{##1\/}* in the definition of
*\nextii@* to allow for the fact that font change instructions might occur
in this argument.

\andsmall If we have a multi-key *\cite*,
\setbox0\hbox{\<key\>$_{\text{1}}$}
\setbox1\hbox{\<key\>$_{\text{2}}$}
**
\cite{"box0,"box1,...}
**
then \<key\>$_{\text{1}}$ will give a warning message like
\setbox0\hbox{\<key\>$_{\text{1}}$}
**
Warning: No \label found for "copy0.
l.35 ... \cite{"copy0}
**
while
\<key\>$_{\text{2}}$ will give a warning message like
\setbox0\hbox{\<key\>$_{\text{2}}$}
**
Warning: No \label found for "copy0.
l.35 ... \cite{"copy0}
**
Although it would be nicer if we got a single message involving
\setbox0\hbox{\<key\>$_{\text{1}}$}
\setbox1\hbox{\<key\>$_{\text{2}}$}
**
l.35 ... \cite{"box0,"box1,...} 
**
this doesn't really seem worth worrying about.
\endsmall

The *.bbl* file will have *\bibitem*'s, but the definition of *\bibitem*
 is found only in
the file *bibtex.tex*.  However, we will state
\C**
\let\newblock=\relax
**
even though *\newblock* occurs only in the *.bbl* file that is read in after
the *bibtex.tex* file;  the reason for this is that different styles might
want to change the definition of *\newblock*. (Many \latex\ style files
define *\newblock* to be *\hskip.11em plus.33em minus.07em*, but the default
\lamstex\ style leaves no extra space between various parts of a
bibliographical entry.)

Similarly, we define a default routine
\C**
\def\beginthebibliography@#1{\rm          "8BTHEBIB"8
 \setbox0\hbox{#1\ }\bibindent@=\wd0
 \bigbreak
 \centerline{\smc\bibliography@W}%
 \nobreak\medskip
 \sfcode`\.=1000 \everypar{}\parindent=0pt}
**
which will be used by the
**
\begin{thebibliography}
**
that occurs in the *.bbl* file; style files can redefine this, 
to produce different sorts of formatting for the information in the *.bbl*
file. 

\section{The {\tt bibtex.tex} file} The file *bibtex.tex* is read in right
before the *.bbl* file; its purpose is to make sense out of the various
\latex\ macros that are going to appear.

The file begins
with 
\CC**
%\input cd.tox
"2
%\input islands.tox
"2
%\input bib.tox
"2
%\input alignat.tox
"2
%\input lists.tox
"2
%\input cardord.tox
"2
%\input anynum.tox
"2
%\input dblacc.tox
"2
%\input literal.tox
**
(As in section~\Sref{GENDEFS}, we are using double horizontal lines for
code that is in the subsidiary file *bibtex.tex*, rather than in
*lamstex.tex* itself).
Although these
lines are commented out, it might be wise to uncomment them,
if it turns out that adding the extra material from *bibtex.tex* unduly
strains the implementation of \tex\ that is being used.

This is followed by
\CC**
\catcode`\@=11
\let\alloc@=\alloc@@
**
since we will be using a *\newcount* and *\newdimen*
(compare page~\ref{NEWALLOC}).

Next we have to deal with the fact that the *.bbl* file usually begins
with things like
**
\newcommand{\noopsort}[1]{}
\newcommand{\printfirst}[2]{#1}
**
and perhaps there will be *\newcommand*'s for control sequences without
arguments also. So we have to interpret *\newcommand* correctly.

For a situation like
\Litbox0=**
\newcommand{\foo}{bar}
**
$$\box0 \tag"\style{\bf A}"$$
where a control sequence *\foo* without arguments is being defined, we
can simply let
*\newcommand#1* mean *\define#1*.  But the general case is more complicated.

First we define *\args@* so that *\args@1* makes *\toks@* be the token list
*##1*, and *\args@2* makes *\toks@* be the token list *##1##2*, etc\.~(we
want the double *##*'s because *\toks@* will then be used within an *\edef*).
The definition looks pretty strange,
\CC**
\def\args@#1{\count@=1 \toks@={}%
 \loop
 \edef\next@{\toks@={\the\toks@########\number\count@}}%
 \next@
 \ifnum\count@<#1 \advance\count@ by 1 
 \repeat}
**
because we have the {\it octuplet\/} *########*, even though we want to
end up with only a pair *##*.  The reason we need this octuplet is 
that the *\loop...\repeat* construction (section~\Sref{LOOP}) 
defines *\iterate* in terms of `*...*';
when this definition is made,
 the octuplet *########* then coalesces into a quadruplet
*####* (unfortunately, even the redefinition of *\loop...\repeat* doesn't get 
around {\it this\/} problem), 
 and then the *\edef* turns this quadruplet into a pair *##*.


Now that *\args@* is defined,  a situation like
**
\newcommand{\foo}[2]{...}
**
can be taken care of with
\Litbox0=**
\def\newcommand#1[#2]{\args@#2
 \edef\next@{\noexpand\define\noexpand#1\the\toks@}
 \next@}
**
$$\vcenter{\box0}\tag"\style{\bf B}"$$
For example, 
**
\newcommand{\switchargs}[2]{#2#1}
**
first uses *\args@2* to make *\toks@* be the token list *##1##2*.
Then the *\edef* makes *\next@* be
**
\define\switch#1#2
**
so we end up with
**
\define\switch#1#2{#2#1}
**

For the general case we must use
\CC**
\def\newcommand#1{\def\nextiv@{#1}%
 \def\nextii@[##1]{\args@##1%
  \edef\next@{\noexpand\define\expandafter\noexpand\nextiv@
   \the\toks@}%
   \next@}%
 \def\nextiii@{\edef\next@{\noexpand\define
  \expandafter\noexpand\nextiv@}\next@}%
 \def\next@{\ifx\next[\expandafter\nextii@\else\expandafter
  \nextiii@\fi}%
 \futurelet\next\next@}
**
Thus, we first save *#1* in *\nextiv@*, and then use a *\futurelet* to
see if the next token is *[*.  If it is,
 we use *\nextii@*, whose definition is
based on ({\bf B}), except that
we need
**
\expandafter\noexpand\nextiv@
**
to get back the *\noexpand#1* (compare pages~\ref{EXNE} and ~\ref{EXNE2}).
 If the next token isn't *[*, then we use
*\nextiii@*, based on ({\bf A}), again
using 
**
\expandafter\noexpand\nextiv@
**
to get back the *\noexpand#1*.


We also need to replicate the definitions of several special commands
from \latex:
\CC**
\def\em{\ifdim\fontdimen1 \the\font>0pt \rm\else\it\fi}
\def\mbox{\leavevmode\hbox}
**
(The actual definition of *\mbox* in \latex\ is
**
\def\mbox#1{\leavevmode\hbox{#1}}
**
 but the above definition works
just as well [and even allows category changes, if that matters].)


To deal with the various items of the bibliography, we will need a new
counter 
\CC**
\newcount\bibitemcount@
**
for automatically numbered items, and a dimension
\CC**
\newdimen\bibindent@
**
for the hanging indentation of items.

A *\bibitem*, which is written by \bibtex@, might have an ``optional
argument'' *[...]*, so we will need maneuvers similar to that for
*\newcommand*. 
The case
\setbox0\hbox{\<key\>}
**
\bibitem[...]{"copy0}
**
will call
**
\bibitem@{...}{"copy0}
**
while the case
**
\bibitem{"copy0}
**
without the optional argument will call
**
\bibitem@{\number\bibitemcount@}{"copy0}
**
where *\bibitem@#1#2* takes care of making the \<key\> *#2*
act like a *\label* with
the value *#1*, and then printing *#1* at the beginning of the
bibliographical data that follows:
\CC**
\def\bibitem{%
 \def\nextii@[##1]##2{\bibitem@{##1}{##2}}%
 \def\nextiii@##1{\global\advance\bibitemcount@ by 1
  \bibitem@{\number\bibitemcount@}{##1}}%
 \def\next@{\ifx\next[\expandafter\nextii@\else
  \expandafter\nextiii@\fi}%
 \futurelet\next\next@}%
**

In order for *\bibitem@#1#2* to make *#2* act  like a *\label* with
the value *#1*, we simply have to
**
{\def\thelabel@{#1}
 \let\thelabel@@=\empty \let\thelabel@@@=\empty 
 \let\thelabel@@@@=\empty
 \label{#2}}
**
---remember that *\label{...}* will always make sense when *\thelabel@* is
defined, and will record the value of this label in terms of 
*\thelabel@*, \dots, *\thelabel@@@@* (we only care about *\thelabel@*,
since it is used for *\ref*, the only thing used by *\cite*).

And then we start the bibliographic entry with
**
\par\hangafter 1 \hangindent=\bibindent@
\noindent@\hbox to\bibindent@{#1\hfil}\ignorespaces
**
So the definition is
\CC**
\def\bibitem@#1#2{%
 {\def\thelabel@{#1}%
  \let\thelabel@@=\empty \let\thelabel@@@=\empty
  \let\thelabel@@@@=\empty
  \label{#2}}%
 \par
 \hangafter1 \hangindent=\bibindent@
 \noindent@\hbox to\bibindent@{#1\hfil}\ignorespaces}
**

Finally, as soon as we hit the
**
\begin{thebibliography}{...}
**
we want everything to be properly set up. Hopefully, this is the only
*\begin* that will occur  in the *.bbl* file.
So we give an error message in any other case:
\CC**
\def\begin#1#2{%
 \def\next@{#1}\def\nextii@{thebibliography}%
 \ifx\next@\nextii@
 \beginthebibliography@{#2}%
 \else
  \Err@{I can't deal with \string\begin{#1}}%
 \fi}
**
Recall that *\beginthebibliography@* (page~\ref{BTHEBIB}) prints the heading,
and sets everything else up properly.


At the very end of the file we will encounter
**
\end{thebibliography}
**
Again, hopefully this is the only *\end* that will occur in the *.bbl*
file, and we define
\CC**
\def\end#1{%
 \def\next@{#1}\def\nextii@{thebibliography}%
 \ifx\next@\nextii@
 \else
  \Err@{I can deal with \string\end{#1}}%
 \fi}
**
(The fact that we are redefining *\end* isn't important, since the
definitions of *bibtex.tex*, together with the *.bbl* file are all read in
within a *\begingroup"allowbreak..."allowbreak\endgroup* region
(page~\ref{UBTBG}.) 

Finally, we reassign *\alloc@* its original definition from *plain* \tex@,
and make *@* active:
\CC**
\def\alloc@#1#2#3#4#5{\global\advance\count1#1by\@ne
 \ch@ck#1#4#2\allocationnumber=\count1#1
 \global#3#5=\allocationnumber
 \wlog{\string#5=\string#2\the\allocationnumber}}
\catcode`\@=\active
**


\chapter \CS{purge}'ing and \CS{unpurge}'ing\endchapter
There's nothing mysterious about *\purge* and *\unpurge*---they simply
read in a *.tox* or *.tex* file:
\C**
\def\unpurge#1{\input #1\relax}
\def\purge#1{\input #1.tox\relax}
**

Each *.toc* file clears up the memory space used for certain control sequence
definitions, 
by redefining these control sequences.
Control sequences meant for the user (those without *@* in their names)
are set equal to  *\undefined*, which \lamstex\ always keeps undefined,
so that their use will give an error message. On the other hand,
control sequences used internally by \lamstex\ (those with *@* in their
names) are simply set equal to *\relax*.  For example,
the file
**
lists.tox
**
which eliminates everything for making lists, starts
(again, as in section~\Sref{GENDEFS}, we use double horizontal lines
for code in subsidiary files) 
\CC**
\catcode`\@=11
\let\listformatbi@=\relax
 . . .
\let\listformtmi@=\relax
 . . . 
\let\listformatti@=\relax
 . . .
\let\listformate@=\relax
**
thereby removing from memory the initial definitions 
of section~\Sref{liststy}.

Then, for the definitions in section~\Sref{liststy2}, we
\CC**
\expandafter\let\csname list@P1\endcsname=\relax
 . . .
\expandafter\let\csname list@Q1\endcsname=\relax
 . . . 
**
We {\it don't\/} bother with counters like `*\list@C1*', or any thing else
 created with a *\new...* construction, because it would create confusion
if we had to restore them in the *.tex* files---each *\newcount* construction
will use up another possibility for a counter, even if we happen to be using
the same name as before. *\newif* works differently, so flags
are set equal to *\relax*, and we also
\CC**
\let\list@@C=\relax
 . . .
**
Intermingled with these redefinitions we also have
\CC**
\let\keeplisting=\undefined
\let\list=\undefined
\let\runinitem=\undefined
 . . .
**
And at the very end we 
make *@* active again,
\CC**
\catcode`\@=\active
**

On the other hand, the file *lists.tex* essentially consists of all the
definitions for *\lists*, except for things like
**
\expandafter\newcount\csname list@C1\endcsname
**
that aren't removed by *lists.tox*.


