The Regimental Number, as well as the later Social Insurance Number and Service Number provided Canadian soldiers with a unique means of identification.
The Canadian Army assigned numbers to Other Ranks (only) up to and including the Second World War. Officers began to receive Regimental Numbers towards the end of the 1939-45 conflict, and after the war, Regimental Numbers were assigned to soldiers in both the Regular and Reserve forces until the adoption of the Social Insurance Number as an identifier. The SIN was replaced in the 1990s with Service Numbers once more.
Often, the last name of a soldier coupled with the last three digits of his number were used to identify him (for example, web gear and clothing issued to an individual would often be marked with the last name and "last three" - ie SMITH 607.)
Other Ranks were assigned a Regimental Number based on the unit he joined.
In the First World War, a document entitled Canadian Expeditionary Force, Instructions Governing Organization and Administration outlined the following:
In the Second World War, every unit was assigned blocks of numbers, prefixed by a letter indicating the Military District in Canada in which the unit was based. There were 11 military districts in Canada, numbered from 1 to 13 (with 8 and 9 left out), and Regimental Numbers thus were prefixed with the letters A, B, C, D, E, F, G, H, I, J, K, L or M. Officers were largely identified by name and rank only.
During the Korean War, with the issue of the new monel metal ID discs, numbers identified the Military District in which the soldier was recruited.
Social Insurance Numbers
At about the time of Unification, the military moved to using the Social Insurance Number in place of the Regimental Number, and this was done up unto the 1990s.
Personal Records Identifier (PRI) ("Service Number")
One commonly held belief is that the SIN (often redundantly called a "SIN Number") could potentially lead to discrimination based on geography, as the first digits of SIN often identified where the bearer of that number was living when the number was assigned. A new series of Service Numbers (officially called a PRI, or Personal Records Identifier, but commonly called Service Number or SN both officially and unofficially) were introduced, in nine character format, with the first character being a letter and the following characters being Arabic numerals. The numbers appeared in the format XXX XXX XXX on the ID disc but was usually written XXXXXXXXX in documentation.
Two references are in print detailing the unit blocks of numbers, for the First World War:
and the period surrounding the Second World War: