Scripting Pages 4 vs. Pages 5

I am in charge of maintaining an Applescript application that was originally written in AppleScript Studio. I am now converting it to ASObjC. Because Apple has kindly diminished the latest Pages by removing Applescript (which I hope will eventually be fixed), I would like some code that would check and ensure that Pages 4 is running and not Pages 5.

Does anyone know how to do this (determine which version is running) in AppleScript? It would also be a nice feature if I could determine early in the program is Pages 4 is even available.

Model: Mac Pro, Late 2013
Browser: Safari 537.75.14
Operating System: Mac OS X (10.8)

You could start by asking for the app’s version…