Export - Import Songs

I try to organise my setup a bit better and part of this is to define a useful structure / organisation for the rackspaces and songs.

During this journey I learnt that it is possible to export songs and later import them into a new gig. As part of the import all required rackspaces / variations are also imported. Very nice and useful.

My question is now: what data is part of the exported song file and what additional data like rackspaces or gigfiles are referenced by the exported song. In other words: what needs to be unchanged to support a song import in the future? I assume the original gig needs to be available and should be stored in the same place … but that only guessing?

What I also discovered is that the MSB/LSB/PC numbers assigned to a song will not stored and imported into the new gig. Is there an option to keep these numbers as a type of universal identification for the song ?