UPnP and Rules Order

[LinuxTracker]

The question has been raised before of whether UPnP (rdr-anchor "miniupnpd") opened ports are effected by Rules.

If so, the followup question is "Does UPnP effectively reside at the top or bottom of the Rules stack?"

I know it's a basic question, but I've been searching for a while and haven't found a definitive answer.

I've seen that diags like pfctl -sr and pfctl -s rules -vv consistently show the UPnPd rdr anchor at the bottom of the list.
That seems to indicate UPnP is governed by Rules and is relegated to the bottom of the Rules stack; but I'm not certain of that.

Can someone provide clarification?