... rules:— Data+CF-Poll, Data+CF-Ack+CF-Poll, CF-Poll, and CF-Ack+CF-Poll shall only be sent by a PC.— Data, Data+CF-Ack, Null Function, and CF-Ack may be sent by a PC or by any CF-Pollable STA. ... by the PC, using the CF-ACK indication (Data+CF-ACK, Data+CF-ACK+CF-Poll,CF-ACK, CF-ACK+CF-Poll, or CF-End+ACK) sent after a SIFS. Such a frame directed to a non-CF-Pol-lable STA shall be acknowledged ... ACK 2 or 3 Directed MMPDUData(dir)+CF-Poll{+CF-Ack} – Data(dir)+CF-Ack – {CF-Ack(no data)}2 Poll and ACK sent with MPDUsData(dir)+CF-Poll{+CF-Ack} – CF-Ack(no data) 2 Poll of STA with empty...