cgagnon said:
If you had your passport stamped from going back and forth through the US or something then you have to send an updated photocopy of your passport the bulletins are on the CIC website.
I don't know about anyone else, but the US and Canada don't seem to stamp my passport as a general rule.
I did know that in order to flag pole at the border, I had to get a stamp in my passport (to demonstrate I had been outside Canada, apparently). For non-US citizens, the protocol is to give them an "administrative refusal" - they stamp a piece of paper and send the foreign national back to Canada and apparently that's sufficient. But CBP cannot refuse entry to a US citizen (much like CBSA cannot refuse entry to a Canadian citizen). I had to park and go inside the secondary inspection building, stand in line and get it stamped. The second US stamp in my passport in five years.
Plus, since I normally use Nexus, I have minimal interactions with immigration folks from either Canada or the US.
I do hope they accept copies!