Labels inscribed Par Avion or equivalent, which means by air.
France had the first example in black on red paper (August 17, 1918); the UPU adopted a standard blue colour in 1922 for affixing to material carried by air.
Stumble it!
Disclaimer: The views expressed by contributors are not neccessarily those of this website. Every care is taken to ensure that the contents of this site is accurate, but the publisher takes no responsibility for errors. While reasonable care is taken when accepting advertisments, the publisher cannot accept any responsibility for any resulting unsatisfactory transactions, but will investigate any written complaints. Acceptance of advertisements does not neccessarily mean endorsement of the product or service.
© 2007, 2008 The Philatelic Database
