A midi record represents a sequence (or a subset of the sequence) of elements:

• instrument-change
• midi-device
• midi-instrument
• play

The data for each of these elements are stored in separate tables with corresponding keys in the midi table.

A midi record can belong to one of two things

• a sound record, which is a type of music_data record, foreign key sound_id
• a score-part which is a type of part_list_item, foreign key score_part_id