[Discussion] What should I put in CSV file when training?

In this CSV file: https://github.com/deezer/spleeter/blob/master/configs/musdb_train.csv

The first column states that it has the mixture.wav files. I would like to confirm, are these files the full song with all the instruments/vocals in it? Also the other columns show vocals.wav and drums.wav. Do these files contain the vocals or drums only? Or do they contain the song with the vocals or drums removed?

I am planning on training spleeter to remove the sound of a new instrument. So when I do the training, should I put the full song in the first column, and the sound of just the instrument in the second column?