By means of this spell, a curious mage could find out the school another wizard specialized in, if any. This was mainly used to determine if a spell caster was a bone fide representative of, or expert in, his or her school of magic. Nothing was learned if the target was not a specialist in their school, or was a priest, or had no spell casting ability. This spell could be cast on a subject without them noticing, but most mages would be offended if they found out they were being spied upon.
Verbal and somatic components were necessary, as well as a small tube made of paper or vellum.