When Permanent Residence processing is nearly completed, the applicant is required to submit the passport for a visa which is essentially the Permanent Residence Visa. I am not sure about its validity. Its either 40 days, 2 months or 1 year. Applicants which applied for PR outside Canada then use this visa to come to Canada. On the airport at Canadian port of entry , their final processing is done, and they are (among other things) given Landing papers which are very important. Then once in Canada, they apply for the actual PR plastic card.
If the applicant was already inside Canada, then there are two ways to do the final step.
1. Contacting the Call Center to request an appointment at a local CIC to finalize processing and getting Landing papers and also applying for the actual plastic PR card.
2. Flagpoling at any Canadian/US border. It means applicants just cross Canadian border and go to US soil and then come back to the Canadian port of entry. For flagpoling, one doesn't need a US visa since temporary residents of Canada with valid work/study permits are exempted to have US visa if they only visit US and come back to Canada. (under Regulation 190 (3)(f)(i) and (ii))