Hi Harvey!
Yep, you're quite right.
The at sign in the Inaternatuional Morse Code is the letters AC combined
into a single character.
While I've not heard anyone use it yet, there was a mention the other day on
this list of an Email address being used in an address for traffic routing,
so it's clear to me that the opportunity to use it is out there.
The person who originally told me about the at sign being added must have
had dyslexia because he clearly told me it was CA, but Wikipedia
straightened me out there.
73,
Dave