If--
(a) an indictment relates to an instrument that is written or printed, or partly written and partly printed, or
(b) it is necessary to make an averment in an indictment with respect to an instrument that is written or printed, or partly written and partly printed,it is sufficient to describe the instrument by any name or designation by which it is usually known, or by its purport, without setting out a copy of the instrument, or otherwise describing the instrument, and without stating the value of the instrument.