If you look at an access point (AP) in detail mode, you can see that it has a base radio MAC address and a fast ethernet MAC address. In addition, that is the base radio MAC address and it changes with the wireless LAN (WLAN). You actually see the Basic Service Set ID (BSSID), which is in the form of a MAC address. It is incremented off the base radio MAC address.
The decode ring works in a manner that it takes the base radio MAC address and then either counts down for 802.11b/g or counts up for 802.11a by the WLAN number. Click Wireless and then 802.11a or 802.11b/g in order to see the base radio MAC. This behavior only applies to VxWorks based APs while the IOS APs do the reverse, i.e. 802.11b/g increments up and 802.11a goes down.
If a base radio MAC is 00:0B:85:23:D0:50, for example: