gEDA-user: pcb refdes name restrictions?

[Peter Baxendale]

Another dumb question. I teach a class of undergraduates about ECAD and
this year abandoned commercial tools in favour of geda. Students being
students, they tend to try things I wouldn't think of doing. Today, a
couple of them decided to be creative and on their schematic used names
like "CONNpower" and "CONNsignal" for refdes values. Whilst I thought it
unconventional and probably inadvisable, I couldn't offhand see why they
shouldn't do that.

Gsch2pcb happily produced a netlist and pcb file which both looked fine,
as far as I could tell. But when loaded into pcb, optimising the netlist
causes error messages such as "Can't find CONN pin 4 called for in
netlist".

So does pcb require that all reference designators be in the form of a
string followed by a numerical value? If so, are there any other refdes
restrictions I should know about? Given time, they're bound to find
them...

Thanks,
PB