Yeah. I have a TSL Patcher currently setup to edit the BattleMusic slot of a .GIT file. It changes the original battle music ID to one corresponding with a newly added 2da line. I ran two instances of this TSL Patcher just now and here are the results:
After the first run the battle music was listed as 100 within the .GIT (and Windows showed that the .MOD had been edited recently). After the next run, the battle music listed as 112 and Windows again showed the .MOD had been recently edited.
This means it was extracting the .GIT, editing it to correspond with the .2da, then repacking it.