will get Immigrant visa from Canada soon

Hi, several months ago I found the rules on the Canadian immigration visa expire date at the website:

http://www.cic.gc.ca/english/

It mentions things like how many months you can have before the last date you can land which shows on your immigration visa placed on your passport. It also mentions that the visa expire date cannot be beyond your passport date etc.

Unfortunately, I cannot find it anymore from the above website.

Can anybody help me to find it out? Or do you know the exact rules on the expire date?

Thank you!!