I've been seeing this #nnn pattern in SY cards a few times, but I can't find any mention of it in the documentation. I'm guessing it's an AWG specification, but then I see something like this:
SY D = #12/in
So maybe #12 specifies 12 AWG in m and #12/in is the same in in?
Yes, the wire gauges like #12 etc. are just predefined symbols that are the radius of that (AWG) gauge of wire, given in metric.
If you're using a GS card to specify dimensions in inches, then you need to divide by in to convert those predefined wire radii to inches — and then the geometry transformation will turn them back to meters, along with everything else, after the whole deck is read in.
mm, cm, in, and ft are also predefined symbols that equal the length of that unit in meters (i.e. 0.001, 0.01, 0.0254, 0.3048).
