I looked at it fairly quickly; but it seems it's just the component build #. (Check Patch-x.MPQ for component.wow-data.txt)
Contents:
Code:
<componentinfo format="1">
<component name="wow-data" version="11723" />
</componentinfo>
Current ver seems to be 11723 according to the exe, and the above file.
Seems WoW just loads the XML and grabs the 'version' string from it then does a compare to see if it matches.
Check the function at 0x95C610 (the only actual call that uses the 'base' string that I could find)