BNAPS Railway Post Office Study Group

RPO glossary
MT-1 Albert and Salisbury RPO postmark dated 3 Aug. 1931
Train 255, 3 Aug. 1931
QC-98 Levis and Riviere-du-Loup RPO postmark with RPO clerk's name, J. A. Dionne, dated
                     18 Dec. 1915
(RPO clerk name)
Train 45, 18 Dec. 1915
RY-87 Halifax and  S.W.R'Y. RPO postmark dated 18 May 1910
East, 18 May 1910
SN-10 Hamilton Canada duplex postmark used at GTRy station dated 22 Nov. 1910
11 AM, 22 Nov. 1910
Duplex used at GTRy station
Mail slot in the railway mail car

Mail slot in the railway mail car

The photo was taken by Robert K. Lane at the Edmonton Railway Museum.

Here is a glossary of terms used by RPO collectors.

Postmark - Sometimes called "cancellation", recognizing that a postmark becomes a cancellation only when it defaces a stamp. Most railway hammers were used both as cancellation devices and for the application of postmarks and transit markings.

P.C., M.C., R.P.O. - A rail car equipped and staffed for handling mail. P.C. (= Postal Car) appears on some early postmarks. M.C. (= Mail Car) was the term that followed and also appears on some postmarks. R.P.O. (= Railway Post Office) is the most recent and most common expression. It appears on many postmarks.

RPO - A term often referring to any postmark used on a rail car (e.g.: "She collects RPOs from Quebec").

Listing - The entire entry for any RPO postmark of a given type. Each major listing is represented by a Listing Number, as found in the RPO catalogue compiled by Ross Gray.

Sub-Listing - Within the permanent lettering of a given postmark, there can be one or more variations that indicate such things as direction, route, time mark, clerk or steamer name. These variations do not constitute a new major type of postmark. They are listed as subtypes under a major listing number.

Listing Number - The listing of the railway cancellations in the RPO catalogue is divided into sections based on geography or purpose. Each section is assigned a prefix of one or more capital letters, as follows:

Newfoundland & Labrador
Railways and Routes
Station Offices
Ticket Stamps
Royal Train

Set - Includes all removable slug data within the center of a hammer, specifically, the day, month, year, train number, direction and/or time mark.

Indicia - Includes only that data in the set above the date, specifically, the train number, direction or time mark. This is somewhat of a misnomer, but is in common use.

  • Train Numbers - Odd numbers indicate trains that went north or west. Even numbers indicate trains that went south or east.
  • Direction Marks - NORTH, SOUTH, EAST, WEST, N, S, E, W
  • Time Marks - AM, PM, or 9:00 AM, NOON, etc. (In Newfoundland, a letter sometimes appears above the date, giving some indication of time).

Hammer - A cancellation device of steel, rubber or other composition containing permanent, non-replaceable lettering, as shown in each listing under "Postmark". Most listings are known with two or more hammers. Identification of each of these multiple hammers varies from simple to difficult, depending on individual characteristics, but all hammers for any given listing will read alike in all major components.

Proof - Postmark registered in one of the several Pritchard & Andrews ledgers prior to delivery of the hammer by the maker against a government requisition.

N.I.P.B. - "Not in the Proof Book". Many hammer proofs were not available for inclusion in the proof books.

O.P.K. - "Only Proof Known". Listings with this designation are known only from the proof strike, and may or may not have been put into actual service.

O.D.O.K. - "Only Destruction Order (strike) Known". Listings known only from strikes in the official register prior to the destruction of the hammer.

ERD - Earliest recorded date of use; also EKD (earliest known date).

LRD - Latest recorded date of use; also LKD (latest known date).

Facing Slip - An approximately 3" x 5" piece of paper, usually showing run and clerk strike. The slip of paper is placed in mail bags after sorting to identify the mail clerk involved.

Rarity Factor (RF) - The RF of any given listing in the RPO catalogue is based on the period of use of the cancelling devices for that listing.

Here are several RPO examples with explanations.

RY-30.31, circle style RPO, no hammer designation, 9 May  1896, EAST direction RY-30.31 (RY designates a "Railways & Routes" category)
Circle style RPO, no hammer designation
EAST direction
MY 9 / 96 (9 May 1896)
RY-30.12, Hammer B, 10 August 1888, WEST direction RY-30.12
Circle style RPO, Hammer B
WEST direction
AU 10 / 88 (10 August 1888)
RY-31.01, LOCAL Hammer 1, 27 June 1893, EAST direction RY-31.01
Circle style RPO, "LOCAL" Hammer 1
EAST direction
JU 27 / 93 (27 June 1893)
MT-257, circle style with larger spacing between the circle and the RPO name, 1897 MT-257 (MT designates a "Maritime" category)
MONCTON & QUEBEC / M.C. (M.C. = Mail Car)
Circle style with larger spacing between the circle and the RPO name
Mail Car without a hammer number
?? ? 79 (error for "97" since the stamp was issued on 19 June 1897)
WT-778.01, Squared circle style, Hammer No. 1, 23 October 1908 WT-778.01 (WT designates a "Western" category)
SOURIS & WINNIPEG / M.C. (M.C. = Mail Car)
Squared circle style, Hammer No. 1, no indicia
OC 23 / 08 (23 October 1908)

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This page was last modified on 2024-01-02