Supposedly, concept designs of the gattling gun Harrison is seen wielding in the trailer as he fights Klingons refers to it as "April's Gun" beginning a theory that John Harrison is an alias for Robert April. But of course, according to half of fandom, the character has to be Khan, so now we believe it's an alias of Khan. Or Gary Mitchell. "April's Gun" is now believed to mean "gun designed in the month of April." Yes, Abrams or Orci or one of those dicks confirmed Cumberbatch is playing a "canon character." Of course since there is a Harrison in TOS that doesn't really clarify anything.