a printed impression made directly from a <#die>.  See also: <#largedie=Large Die Proof> and <#smalldie=Small Die Proof>.

<#postalmark=postal markings> applied to a <#cover> indicating <#forwarding> for delivery, or a failed attempt to deliver mail, such as "Address Unknown" or "Forwarding Time Expired".

a post office no longer in operation, or in operation with a different name.

mail that has been treated to prevent the spread of a contagion.  Also see <#irradiate=Irradiated Mail>.

<#revenue=revenue stamp> for payment of taxes on distilled spirits.  Used from 1950 to 1959.  <#scott=Scott> RX.