ath(4) sysctl tuneables

[FreeBSD Daemon]

dear list,

I own a ath(4) card and would be interested in information about the the 
meaning of these ath sysctl tueables.
Which can be changed? Which values can these changeable tuneables take?

hw.ath.hal.dma_brt: 2
hw.ath.hal.sw_brt: 10
hw.ath.hal.swba_backoff: 0
hw.ath.dwell: 200
hw.ath.calibrate: 30
hw.ath.outdoor: 1
hw.ath.countrycode: 0
hw.ath.regdomain: 0
hw.ath.debug: 0
hw.ath.dump:

If hw.ath.debug is set then here do the debug messages go?

TIA

zheyu