a print made from a <#die> that has not yet been completely engraved, generally made to check the phases of engraving, also known as a <#progproof=progressive die proof>.

a number assigned by the <#scott=Scott Catalogue> to all <#stamp=stamps> with a common <#design>.

A <#perf=perforator> that applies lines of perforation holes in only one direction.

<#perf=perforations> that meet perfectly in the corners of stamps.

term used by the <#usps=United States Postal Service> for stamps intended for use on mail.