Man pages matching name midi_msg_callback in section 3alleg4:

midi_msg_callback.3alleg4.en	debian 10 / allegro4-doc
midi_msg_callback.3alleg4.en	debian 11 / allegro4-doc
midi_msg_callback.3alleg4.en	debian 12 / allegro4-doc
midi_msg_callback.3alleg4.en	debian 13 / allegro4-doc