I am about to update from the 1.5 air sdk to 2.5 air sdk. My application uses a version number schema of 4 digits seperated by dots, i.e. 18.104.22.168. In this document http://kb2.adobe.com/cps/873/cpsid_87300.html it says use "This field must contain one to three dot-separated numbers"
Can I not continue to use my 4 digits seperated by dots
It appears to require just the 3. That's probably more convenient for developers, though, so you don't have to go tweak the xml in the event of a minor security release.