Man pages matching name allegro_sub_version in section 3alleg4:

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