## Runtime page

The Runtime page shows information about run-time libraries. When packaged, platform plug-ins deliver all of their Java classes in JAR libraries.

You can also determine exporting rules for your libraries. By default, no classes in your libraries can be seen by others. This is appropriate if your plug-in is not meant to be extended. If your classes should be visible to other plug-ins, the libraries must be exported. You can export the entire library or just a subset of packages.

The first time a class is accessed from one of your plug-in's libraries at runtime, the plug-in gets activated. In 3.0, this activation is selective. You can specify the conditions when your plug-in should be activated at runtime, thus potentially reducing overhead and memory footprint. This functionality is only available for plug-ins that have an OSGi bundle manifest.mf file. Therefore, if you want to take advantage of this functionality, PDE provides a link in the Plug-in Activation section that will create a manifest.mf file for your plug-in with all the correct contents on the fly.