A design registered across Canada can have the CRN number shortened to make it a little easier to read.  The letter “C” indicates that the vessel has been registered in the rest of Canada. The letters CL can be used to indicate that a fitting has been registered everywhere it is required to be registered.  See CSA B51-14 4.3.2 Notes(2) and (3).

4.3.2(2) If a design is registered in all provinces and territories, the CRN stamped on the nameplate and marked on the data report may be shortened to include the designation of first registration plus the letter “C”, e.g., K4567.5C.

4.3.2(3) If a design is registered in all provinces and territories that require registration but not in provinces and territories that do not require registration, the CRN may be shortened to include the designation of first registration plus the letters “CL”, e.g., K4567.5CL. (The “L” means limited.)

We registered this Category “A” breakaway connector Canada wide, starting in Alberta:

0A12396.2 A Category A fitting, 5 digit form originally issued by Alberta Boilers and Safety Association (ABSA) for Alberta use. Copies of the original registration were then sent to the other jurisdictions for reciprocal registration.
0A12396.21 As Accepted by B.C. Safety Authority (BCSA) for use in B.C. (trailing digit “1” added by BCSA for B.C. acceptance).
0A12396.23 As accepted by Technical Safety Authority of Saskatchewan (TSASK) for Saskatchewan use. “3”
0A12396.24 As accepted by Manitoba Office of the Fire Commissioner for use in Manitoba. “4”
0A12396.25 As accepted by Technical Standards and Safety Authority (TSSA) for use in Ontario. “5”
0A12396.26 As accepted by Service de l’inspection de la fabrication (RBQ) for use in Quebec. “6”
0A12396.27890YTN As accepted by ACI Central, Inc. for use in New Brunswick, Nova Scotia, Prince Edward Island, Newfoundland and Labrador, Yukon, North West Territories and Nunavut. “7890YTN”
0A12396.2134567890YTN Same CRN, combined to show Canada wide acceptance.
0A12396.2C The acceptable short-from indicating that this break away connector is registered Canada Wide.
0A12396.124567890YTN The same fitting registration if it was applied for today. Saskatchewan no longer registers Categories A, B, C and G.  B.C. and Manitoba registration would be required because this item is not listed in a B31 standard.
0A12396.2CL The acceptable short-form indicating that the fitting is registered everywhere it is required.

The jurisdictions do not combine the CRN digits to create the Canada wide registration number. It is up to the applicant to do that after all of the provinces have signed off. Be careful of when to use the “C” and “CL” designation. “CL” Can only be used on fittings that are exempt in the provinces not registered.