type "S" , type "N" etc. mortar ?
Masonry cement and cement mortar is rated with letters according to strength:
Type "M" is preferred for stucco, but type "S" may be used.
Type "N" is used for brick veneer. Not only is it cheaper, but can be cleaned off easily.
Type "O" is used when a weak mortar is preferred for historic brick work. Old, soft bricks expand
and move more, and a weaker mortar (supposedly) prevents bricks from "blowing up". Blowing up is when old soft bricks crumble during historic brick rebuilds.
Plastic cement is used in California,and is probably stronger than type "M". Plastic cement is portland cement
with a small amount of a plasticizer instead of lime.
I may be a little wrong on some of these strengths, but this is the best I remember. If anyone can correct me,