[MIDI programming study] Which part of MuseScore's code would I be looking at to understand its MIDI export protocol?

Since musescore is an open source program, I wanted to take the effort in understanding how MIDI exporting as a whole works mathematically in effort to make a miniature DAW using Godot. I'm still totally fresh to programming, but I'm able to get an idea of what's going on when I read code and scripts. What part of MuseScore's code on Github would I be looking at to see how it handles converting its files to MIDI exports?

A good question to ask as well if anyone knows, is the data of music notes stored similar to MIDI inside of MuseScore, or does it have its own directory for RAM and eventually harddisk storage?