The info CHOP can be used across families so often the best place to check for the information you’re seeing in the info CHOP is actually in the family or operator class you’re inspecting. It’s been my experience that much of what’s exposed by the info CHOP is similar (if not directly related to) the class members for a given operator. I usually start there to see what I can learn. In the example of the audio file in CHOP:
I did a little quick experimenting, and it looks to me like export_sernum is related to the exportChanges member. This element shows up across CHOPs, and changes when a channel is exported.