In the server code, in response to a load, you can watch it in stdinhand.c load_command() in the save file which is a compressed version of what looks like a .ini structure file. Just a guess but from the dates this project was started, the developers who put this in probably had no xml option at the time. They apparently wanted a lightweight database that was high enough performance, and text based so that naive users could manipulate it.
Moving a Unit
Set a breakpoint at do_move_unit in control.c, then do a move. Resulting stack most recent order looks like this:
Crikies. They are doing a net IO for every tiny bit of a move transaction. Wow. Wow.
In unitHand.c, set a bp at handle_unit_move Call Stack:
and top loop stuff.