actually.... and at the risk of this snowballing the discussion:
show ap allowed-max-EIRP is deprecated (quite a while ago)
the new command is
show ap debug power-table ap-name <ap> radio [0|1]
this came about because of changes to the way we have to sum up power for multi chain APs together with beam forming etc etc.
The CLI output is lengthy, but it's somewhat self explanatory (read the info at the bottom of the output). As with the previous show ap allowed-max-EIRP it only works for an AP on the controller itself.
tl;dr; there is a new cli command which shows tx powers per rate per bandwidth per modulation per # chains etc.