Single-circle CDS in duplex with a box containing the slogan: "PAQUEBOT/POSTED/AT SEA" in
the right half and 5 horizontal lines in the left half.
This was commonly used in four Canadian ports from the 1920s into the '70s.
* Still thought to be in use according to 2nd. Edition (1987) of Hosking's Book.
** Hoskings uses Studd's rating system (A=common, B=less common, C=reasonably scarce, D=rare) with the added categories: AA=very common and DD=very rare.
* Halifax, Quebec and Vancouver - the newer types all have smaller letters.