EEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications—Amendment 1: High-speed Physical Layer in the 5 GHz band
and it is a part of IEEE802 Part 11 Amendment 1 ("a")
you could get more details here:
Answering on you question: standard defines MAC and PHY for 5 GHz band, thus physical and data link layers in OSI model (https://en.wikipedia.org/wiki/OSI_model)