Man pages matching name register_bitmap_file_type in section 3alleg4:

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