"Consider placing a credit freeze on your files. A credit freeze makes it harder for someone to open a new account in your name. It will not prevent a thief from using any of your existing accounts;"

I've found information about credit/security freezes on the US web sites for Equifax and TransUnion (including legislated costs, by state) but cannot find information about freezes on the Canadian sites. No mention. So if this is an action people may want to consider, where are the details?

What are the detailed implications of placing freezes and how do you start the process?? More information please.