The recommended convention for naming the plug-in archives is
<id>_<version>.jar
Where <id> is the plug-in or fragment identifier and <version> is the full version identifier contained in the respective plugin.xml or fragment.xml. Note that this is a recommended convention that minimizes chance of collisions, but is not required by the Eclipse architecture. For example, the following are valid plug-in archive names:
org.eclipse.platform_1.0.3.jar
org.eclipse.ui.nl_2.0.jar
my_plugin.jar
Internally, each plug-in archive packages all the relevant plug-in or fragment files relative to its plug-in or fragment directory (but not including the directory path element). The archive has the following structure
plugin.xml *OR* fragment.xml
other plug-in or fragment files and subdirectories
META-INF/
Java jar manifest and security files