What does the letter C after the Canadian invention patent number mean?

Hello, you should be talking about the authorization announcement number, right? As follows:

For patents issued after July 1 2004:

Disclosure of application for invention patent

Announcement of invention patent authorization

Announcement that the patent right for invention is partially invalid

U utility model patent authorization announcement

Y announcement of partial invalidation of utility model patent right

Announcement on authorization of patent for design or announcement on invalidation of part of patent right

For patents issued before July 1 2004:

Disclosure of application for invention patent

Announcement of invention patent authorization

Y utility model patent authorization announcement

Announcement on authorization of design patent