Each toolbar should have a version number. The version number is stored in the version parameter of the TOOLBAR tag.eg:
When ever you make a change to your toolbar, you should increment the version number. This is to enable the auto-update feature to work correctly. Unless users have the auto-update feature disabled, the source URL of your toolbar will be checked once a week for updates.
The version number format is major.middle.minor eg: 1.01.001
Increase the major version for major new version releases. The middle version should be updated when significant new features have been added. The minor version should be incremented for minor changes and bug fixes.