Editing Canada Post (section)

===Tracking numbers and barcodes===
{{Further|S10 (UPU standard)}}
Canada Post use 13 digit alphanumeric tracking numbers / barcodes for their pre-printed labels.  Bar codes consist of two letters, followed by eight sequence digits, and a ninth digit which is the check digit. The first two letters are the type of service (RN for registered mail, PG for express post envelopes). The last two characters are the letters CA.  The check digit ignores the letters and only concern itself with the first 8 numeric digits. The scheme is to multiply each of those 8 digits by a different weighting factor, (8 6 4 2 3 5 9 7). Add up the total of all of these multiplications and divide by 11.  The remainder after dividing by 11 gives a number from 0 to 10. Subtracting this from 11 gives a number from 1 to 11.  That result is the check digit, except in the two cases where it is 10 or 11.  If 10 it is then changed to a 0, and if 11 then it is changed to a 5.  The check digit may be used to verify if a barcode scan is correct, or if a manual entry of the barcode is correct. The system of barcode digit checking is referred to as Modulo 11 or Modulus 11 digit calculation.<ref>{{Cite web|url=https://www.canadapost.ca/cpo/mc/assets/pdf/business/3523_en.pdf|title=Registered Mail Envelope Envelope Layout Guide|website=canadapost.ca|archive-url=https://web.archive.org/web/20141116065743/https://www.canadapost.ca/cpo/mc/assets/pdf/business/3523_en.pdf|archive-date=2014-11-16|url-status=dead}}</ref>

Canada Post use 16 digit numeric tracking numbers / barcodes for parcels that originate from a Canada Post post office. The first 7 digits are the reference numbers for the specific post office that the package originated. A Modulus 10 digit calculation is used to verify that the barcode has been read correctly, also referred to as the [[Luhn algorithm]]. USPS and Canada Post both use the same system to verify the barcodes, with a difference that USPS uses a 20 digit numeric tracking number. These types of barcodes are referred to as GS1-128.<ref>{{Cite web|url=http://www.axicon.com/checkdigitcalculator.html|title=Check Digit Calculator{{!}} Check your Barcode|website=www.axicon.com|language=en-GB|access-date=2017-09-14}}</ref>