About STANDARD MIDI FILES (SMF)
The Standard MIDI Files (SMF) Specification defines how to store a sequence of MIDI messages in a file (.mid) so they can be played back in the correct order and timing.
ABOUT SMF AND US COPYRIGHT LAW
Even though an SMF does not contain sounds, it does contain a 'fixation of the performance" representing a "musical work", and therefore may be used to register a musical work with the US Copyright Office, and is subject to the same licensing laws that apply to other recorded audio media (CDs and Cassettes).