mail carried by air, for a fee, from a ship at sea to land.  This obsolete service was intended to shorten the length of time it took mail to cross the Atlantic Ocean.

one in a series of international stamp shows hosted once a decade in the U.S.  Held in New York City in 1947.  A <#stamp> (947) and <#souvenir=souvenir sheet> (948) were issued in conjunction with this show.

a <#cover> that has had its contents examined by civilian or military censors, and which bears a marking evidencing such examination.

a <#block> of stamps from the very center of certain <#sheet=sheets>, that is, a block on which two <#guideline=guidelines> intersect each other.

programs issued in conjunction with <#fdc=First Day> events.  While formerly individualized for each new issue, generic programs are noe used.