Different TX Powers on same country


i have a question about TX powers.
I tried to change the option "country" on some routers and it change the TX Power correctly.
But i know there are two different limits for the EU: 20dBm on IEEE802.11b and 18dBm on IEEE802.11g/n

If i set the 'hw_mode' option to '11ng' the TX power is 20dBm but I'm afraid it is outlaw for EU countries.

Is my doubt right?
Is there something i can do to correctly set the TX power based on the IEEE option?

Thanks a lot for your attention