This attribute shall specify the maximum number of microseconds of an EDCA TXOP for a given AC at the AP. The default value for this attribute is 1) 0 for all PHYs, if qtechdot11QAPEDCATableIndex is 1 or 2; this implies that the sender can send one MSDU in an EDCA TXOP, 2) 3008 microseconds for Clause 17 and Clause 19 PHY and 6016 microseconds for Clause 18 PHY, if qtechdot11QAPEDCATableIndex is 3, 3) 1504 microseconds for Clause 17 and Clause 19 PHY and 3264 microseconds for Clause 18 PHY, if qtechdot11QAPEDCATableIndex is 4.