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radiotap.mcs.format erroneously = greenfield (1)

Idiosyncrasy capturing WLAN frame Tx's between all of my AP's and all of my non-AP STA's with WireShark 3.0.6, 3.0.7 & now 3.2.0 with oldish MacBook Airport Extreme Broadcom 802.11b/a/g/n WLAN interface. None of the AP's & non-AP STA's (except possibly the MacBook itself) support Rx HT_GF preamble PPDU's.

All frames within all blocks of 2 or more unicast HT, QoS Data, A-MPDU frames, except the last frame of each block, have radiotap.mcs.format = greenfield (1) which is erroneous. The last frame of each block has it right: mixed (0).

Thus wlan_radio.11n.greenfield = True (erroneous) in all frames, including the last, of each block, & wlan_radio.preamble (which only appears in the 1st frame of each block) is 8 ┬Ás less than it would be for HT_MF preamble.

This does not happen with blocks of 1 frame (if that makes sense) i.e. wherein a single MPDU is nevertheless processed as an A-MPDU.

Just curious if anybody knows if this misconstruance could be coming from the MacBook's Airport Extreme/Broadcom 802.11a/b/g/n WLAN interface?