scp isn't part of the ssh protocol. It's a command that runs over it.
Out of curiosity, since I wasn't sure which one in particular throwaway2048 was talking about, here are my closest guesses:
927 - Standards - https://xkcd.com/927/
1127 - Workflow - https://xkcd.com/1172/
1323 - Protocol - https://xkcd.com/1323/
Yes, we all know about xkcd, no need to link guys.