Finding devd notification values

I am attempting to get the "mute" key on my Thinkpad T16 to work. I already
use devd for brightness, but I have not guessed what notification value I
need to specify in the 'match "notify"' statement. I could just keep trying
different  values, I guess, but I hope that there is a way to get the event
(ala xev(1)).

I am hoping I can craft a devd statement that will return all notifications
from
match "system" "ACPI"; match "subsystem" "IBM"; match "notify" *;
or something similar. Does devd support anything like this? If so, I should
be able to pipe that to see the value.

Thanks for any clues. I think I once knew how to do this, but my memory has
lost it in hte past couple of decades.
--
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: rkoberman@gmail.com
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683