# Bundles Tab

The Bundles Tab allows you to select the bundles and their start level, which consequently allows you to customize the osgi.bundles and osgi.bundles.defaultStartLevel system properties that the launch configuration will run with.

## Default Start Level

A start level is a positive integer that denotes the default OSGi start level at which a bundle will run. The default start level, which is assigned to all selected bundles, is initially set to 4. This master setting can be changed directly to modify the start level of bundles en masse, or it can be overridden on a per-bundle basis.

## Default Start Status

The start status indicates to the framework whether a bundle should be marked as active after it gets installed. If set to true (the default), a bundle will always be started when the framework is launched. The Default Auto-Start is a master setting that is applied to all selected bundles en masse, but it can be overridden on a per-bundle basis.

## Bundle Selection

Bundles that are to be installed by the framework upon startup must be explicitly checked on this page. By default, a bundle will be assigned the default start level and the default start status, but these values can be overridden on a per-bundle basis by selecting the bundle and editing the start level and status in-place.

There are several buttons available to help you select bundles including an Add Required Bundles button. The Add Required Bundles button should be used often to ensure the subset of bundles you have selected is complete.

Please note that if a workspace bundle has the same ID as a target bundle, the workspace bundle overrides its target counterpart. This behavior can be overridden by deselecting a workspace bundle and selecting its target counterpart.

## Validate Bundles

The Validate Bundles functionality, which can be invoked via the button located at the bottom right corner of the Bundles tab, analyzes the selected set of bundles to find launching startup problems. For instance, missing dependencies, unsatisfied execution environments, incompatible platform filters are a few of the potential problems that may prevent your bundle from running.

By checking the Validate bundles automatically prior to launching option, PDE will run the Validate Bundle function prior to every launch. If problems are found, a dialog showing the error comes up for you to examine and you have the option to continue the launch without correcting the problems or canceling the launch to rectify the issues. Otherwise, if no problems are found, the launch proceeds as normal.