Ancillary Markings. 
ABC 83 ANCILLARY MARKINGS
Webster’s defines the word Ancillary as “helping, auxillary”, and so ancillary markings are those that help process the mail and move it on its way. A very common marking is By Airmail – Par Avion in French or Aerphost in Irish. This is normally seen either printed or on an etiquette (example shown is from a roll). (Figure 1).
Postage due on an international cover is twice the shortfall expressed in gold centimes. This is shown by a “T” in a hexagon or box with the amount due listed in gold centimes. In this case, with the 1d stamp on a post card, it was short ½d which translated into 10 centimes which in turn, became 2 American cents. The US Post Office noted this and added two one cent postage due stamps which were cancelled with a manuscript marking when Miss Heany paid the 2 cents. (Figure 2)
A less common ancillary marking is Printed Matter seen here stamped in blue. (Figure 3). This informs any postal inspector that what might be misconstrued as a first class letter and subject to taxation as underpaid, is printed matter and thus permitted to use the lower rate.
Other markings seen are Express mail, (Figure 4) and Perishable (Figure 5). These markings are often seen on parcel post mail. One marking seldom seen on 21st century mail is the “Eggs” sticker used when fertilized eggs are shipped by parcel post. (Figure 6). Hopefully this would remind the postman to expedite the package and not throw it too hard. If ignored, perhaps the Reconditioned in the Post label (Figure 7) might be appropriate, but probably not very successful..
These markings impart information for the orderly movement of mail and direct attention to specific instructions. Finding some markings can be elusive, but add interesting facets to one’s collection.