Acme tag for when editing man pages

I've been writing more man pages recently that aren't in the usual Manpath and instead of building a new plumbing rule I made a tag

% cat /acme/bin/Man
#!/bin/rc

if(~ $#* 0) {
tags=`{cat /mnt/acme/$winid/tag}
f = $tags(1)
}
if not
f = $1

nroff -man $f