Jusqu-a Airmail Markings- A Study Ian Mcqueen -

An airmail etiquette (blue "Par Avion" label) needed to be "canceled out" or qualified because the flight was unavailable for the remainder of the route.

Originally published in by W.A. Page, McQueen's study was ground-breaking because it categorized a previously neglected field of auxiliary markings. The original 109-page softcover was so well-received that McQueen followed it with a massive Supplement in 1995 that actually contained more pages (163) than the original book. Key features of McQueen's study include: Jusqu-a Airmail Markings- A Study Ian McQueen

The term "Jusqu-à" is French for or "up to" . In postal history, these markings served a critical operational function: they indicated the specific point where airmail transmission ended and surface transport (train or ship) began. They were typically applied when: An airmail etiquette (blue "Par Avion" label) needed