IT and DBM have instruments as well. I don't remember, off hand, how it works for IT. DBM was no problem.
Regarding XM, I'm not sure I understand your comment. 128 rows could be a reference to pattern data ?
Nevertheless, there can be 128 instruments in a XM, and each instruments can store 16 samples. The concept is the following : for this instrument, which sample should be played when a given note is played. As such, you have a map of notes where you assign sample numbers (in the current instrument). Hence the specific information related to each sample. Instruments, here, are some kind of envelope only.
Now, yes, I believe the display mask must be changed. The more I think about it, the more I leaning toward something like that:
instrument 1 -
----sample 1 (sample data)
----sample 2 (sample data)
instrument 2 -
etc.
could take some time to write, though.
