Concepts represented by symbols

*Chaals:
One thing that struck me is that I am not sure if we have set up for the
idea that a preferred term for a concept, in a particular vocabulary, might
be represented by an image or multimedia object rather than a text term...

I had thought about using the foaf:depiction property to allow an image
representation of a concept.  However, reading up on the WWAAC project
suggests to me that foaf:depiction may not be enough, and in fact we would
need something like skos:prefSymbol and skos:altSymbol (which could be
sub-props of foaf:depiction??).  Chaals what do you reckon?

Al.