I would put 802.11a as 3 together with 802.11g, since they have the same rates (and are basically the same tech in a different band, 802.11g feels like 802.11a ported to 2.4GHz plus some extra compatibility stuff).
Re:Wi-Fi Alliance introduces Wi-Fi 6
by WorldMaker on Wednesday October 03, 2018 @02:33PM
(#18133280)
It sounds like the Wi-Fi Alliance doesn't particularly care which one is 1, 2, and 3. They've only strongly defined 4 (n), 5 (ac), and 6 (ax). [1] It also sounds like they don't think enough devices are left in the wild of a, b, g, to worry about branding them.
The best description I've heard for 1-3 was to use roughly the consumer hardware adoption curve which was 1 (b), [briefly] 2 (a), 3 (g).
Most 802.11b and 802.11g devices didn't support 802.11a (due to it requiring 5Ghz), so I'm guessing version 1 is 802.11 and 802.11a isn't part of the version numbers.