iw dev <devname> twpoxer limit in mBm or not

["solsTiCe d'Hiver" <solstice.dhiver@xxxxxxxxx>]

hi.

On ubuntu 18.10 using kernel 4.18.0-10-generic and iw-4.14 on a
Broadcom Corp. BCM43142 wifi interface using wl driver, i run

 sudo iw dev wlp2s0 set txpower limit 21

and iw dev reports back a txpower of 21 dBm

But the doc at https://wireless.wiki.kernel.org/en/users/documentation/iw#setting_tx_power
and the output of `iw dev help` states that the txpower is to be
expressed in mDm not dBm.

So I am confused.

Can I use
suod iw dev wlp2s0 set txpower limit 2100
wihtout frying my card ?

Moreover, how is that even possible given that I have set the regdom
to FR and that max output power is supposed to be 20dBm in Europe ?

Thanks