What does YAO stand for?

Yao - Language code (ETLW)

Yaounde - Cameroon - Airport symbol (OAG)

Yato - NCIC firearms make code (NCIC)

Ytterbium Aluminum Oxide (UWER)

Yttrium Aluminum Oxide (UWER)

Yao (Bantu) - MARC language code - Library of Congress (LCCP)