Should I keep these tracks?

[eurim]

I've imported a song into 3MLE and noticed I have many tracks that seem empty. For example, I have one track with a just this line

/*M 43 */  v7>g32

preceded by many lines of rest. 

Also there are MANY other tracks that looks like this

//#using_extension
//#using_channel = 13    // or whatever target track I'm importing
/*M 0  */  r2.r16y64,0y72,64

In fact I think all the target tracks besides the first one (channel 1) has only this line. Should I keep these or discard them?

What do the "y", "v", ".", and "," represent? How do I interpret these lines?

Also what exactly does the quantization setting do?

Edited October 14, 2018 by eurim

[malokyte]

Not an expert in MML, still learning myself, but I'm confident with some answers.

First // and /* */ indicate comments, and are essentially ignored when read. For example, writing

// this is a comment

would exclude // and everything in the line after it from being "read" by 3MLE. /* and */ make everything between them excluded from being read. For example: 

/* ignore everything here */

Both can be safely removed, and I believe are removed automatically if you select "Optimize Track" in the 3MLE menu.

For the first track excerpt you posted, I believe it's indicating that the entire track is dedicated to playing one note. This is likely a composition thing, as this track is probably intended to play that note with a specific instrument. Typically, you want to keep the note, but you can mute the track and listen to the section it plays in to see if it affects how the piece sounds. If it doesn't, you can probably safely delete the track. Otherwise, you might consider finding a track that's resting at that point and inserting the note there (assuming a solo piece).

I'm not sure what y, ., or , stand for, but v should always be followed by a number, and it indicates the volume of the track from that point onward. v8 is volume setting 8, v9 is volume setting 9, etc. You typically want the volume to be lower for louder instruments (horns typically) and higher pitches, as high volume with loud instruments is painful to listen to, same with high volume with high pitch.

Unfortunately, I'm not sure with the other questions, so I won't risk giving a wrong answer.