3Com WX1200 Reference Manual page 259

Multicast rate—Data rate at which the radio sends multicast frames.
The valid rates depend on the radio type and are the same as the
mandatory rates. The default is Automatic, which sets the multicast
rate to the highest rate that can reach all clients connected to the
radio.
Mandatory rates—Set of data transmission rates that clients are
required to support in order to associate with an SSID on a MAP radio.
A client must support at least one of the mandatory rates. These rates
are advertised in the basic rate set of 802.11 beacons, probe
responses, and reassociation response frames sent by MAP radios.
Management frames sent by MAP radios use one of the specified
mandatory rates.
The valid rates depend on the radio type:
802.11a—6.0, 9.0, 12.0, 18.0, 24.0, 36.0, 48.0, 54.0
802.11b—1.0, 2.0, 5.5, 11.0
802.11g—1.0, 2.0, 5.5, 6.0, 9.0, 11.0, 12.0, 18.0, 24.0, 36.0,
48.0, 54.0
The default depends on the radio type:
802.11a—6.0, 12.0, and 24.0
802.11b—1.0, and 2.0
802.11g—1.0, 2.0, 5.5, and 11.0
Supported rates—Rates that are not mandatory but that the radio can
nonetheless use to send data. By default, all valid rates that are not
mandatory are still supported.
Disabled rates—Data transmission rates that MAP radios will not use
to transmit data. This setting applies only to data sent by the MAP
radios. The radios will still accept frames from clients at disabled data
rates. By default, none of the data rates are disabled.
All rate settings apply specifically to data rates used by radios for
transmission. Radios can accept frames from a wireless client at any valid
rate.
Viewing and Configuring Wireless Services 259