Man pages matching name lzss_unpack_data in section 3alleg4:

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