What does the "#n" after "GENERIC.MP" stand for?

Hi,

Out of curiosity:

~$ uname -r
6.6
~$ uname -v
GENERIC.MP#0
~$ sysctl kern.osversion
kern.osversion=GENERIC.MP#0

This was GENERIC.MP#7 before I ran syspatch and rebooted.

I can't find a reference to this notation. I thought it could have
been the patch version number, but it's obviously not so. Looking on:
https://dmesgd.nycbug.org/index.cgi?do=index&fts=OpenBSD

it appears machines running -current have a higher #number.

--
Ottavio Caruso