Each knowledge base has a version number and build number which is shown on the Knowledge Base Settings dialog...
and on the Home Screen...
The build number starts at 1 and increments on each save of the knowledge base back to the server. The version number also starts at 1 and can be incremented by the user from the Home Screen...
The ability to increment the version number is dictated by the 'Version Creator' permission on the user's account and is controlled by the administrator.
From the Home Screen the user can also list previous versions of the knowledge base via the Version Inspector...
This will present a dialog listing the versions in reverse chronological order, with each version displaying the time and date of when it was archived. When hovering over a listed version certain icons will appear, one for duplicating and possibly one for deleting...
The duplication icon will produce a separate knowledge base in the user's account from the highlighted version - this will default to naming the copy as the name of the knowledge base plus the particular version number. The audit for this copy knowledge base will indicate it has been extracted from the version archive and the actual version number and build number of the copy will be reset to 1 and 1 respectively.
The delete icon will only appear if the user is an owner of the knowledge base and has the ability to increment the versions - deleting individual versions can not be reversed.
If a knowledge base is exported from the home screen then the resulting zip file will contain the current version and all the archived versions.
At runtime the version information can be programmatically accessed using xpertrule.kbversion().