I dug a little deeper to get an idea of what you see in a scm file.
This an empty file made by App Inventor version nb168b build june 19th.
Look at the YaVersion in the text.
So in this case the YaVersion is 167.
The latest change was that the Form_component was incremented to 23.
You can see that in the empty file. Form Version = 23. You should be able to find it.
The change that was made to the form was that the action bar property was deprecated.
You can look at all the changes ever made here: appinventor-sources/YaVersion.java at master · mit-cml/appinventor-sources · GitHub
The authURL is empty. It is filled when you add components to the Screen/Form. Then it says
in the case of App Inventor.
The YaVersions for all builders (Makeroid, App Inventor and AppyBuilder) are different. The Form versions for App Inventor and AppyBuilder are the same but for Makeroid it is different.
So all the builders make aia files and build apk files but internally they are all very different. Keep that in mind next time when you are surprised you can not import your aia in another builder and get errors.