The Star Trek Star Fleet Technical Manual 2.0

“In my view, logic dictates that the “highest” canon is what appears on screen.”

Then you should watch TOS carefully again, as the only time a crew from another Federation starship bore an insignia other than the delta was the three officers we saw in The Omega Glory. The memo is about this production error. There were no other errors prior to this episode, or after.

“BUT. Given that Decker as well as Tracy (and some guest cast in “Courtmartial,” IIRC) bore non-arrowhead ID – well, “I refute it thus.””

Decker’s insignia was not the insignia particular to the USS Constellation. Decker was a commodore and his insignia was to signify that he was a flag officer with a field command. Also, his insignia doesn’t have the department emblem command star that should be present if this was in fact the specific insignia for the Constellation. Fans have added the command star after the fact, but it was never there because it wasn’t supposed to be there. If we would have seen the rest of the Constellation’s crew they would have been wearing the Delta.

Commodore Wesley, in The Ultimate Computer wore the starbase duty insignia, like other commodores serving on starbases. He didn’t have Decker’s insignia because he only took temporary command of the Lexington for the purposes of the war games. We don’t get to see the other officers on the bridge, but they would be wearing the starship duty insignia (i.e. Delta). In fact, anyone serving on a starbase wore the flower emblem (Court Martial, The Ultimate Computer, The Menagerie, etc).

As for Court Martial, when Kirk enters the lounge with McCoy there are officers lined up at the bar giving Kirk grief. These are clearly not crew from the Enterprise, as no one under Kirk’s command would talk to Kirk in that manner. Furthermore, when Kirk walks in the lounge he says “Looks like my class is well represented here.” indicating that he hasn’t seen these men in a while. These officers are from another starship and they are wearing the Delta. On the other hand, Kirk’s ex and jag officer is wearing the same flower that Tracey and other commodore’s wore because she’s serving on a starbase.

There was the outpost duty insignia that we see in Arena and Balance of Terror. We also get to see this insignia in the Strange New Worlds season 1 finale, “A Quality of Mercy”.

In Charlie X, those men who dropped Charlie off on the Enterprise were merchant marines. Again, they didn’t have department emblems on their insignia. Because they didn’t graduate the academy they don’t have the honour of wearing the Delta.

If you watch TOS carefully it’s all very consistent, aside from the one production error with Tracey and his crew in The Omega Glory, which was addressed by the memo. The various insignias we see throughout the series are all based on the duty postings, not ships. So, if you really stand by your “the ‘highest canon’ is what we see on screen” statement then you should just accept the memo and toss out the fan theory that all ships had different insignias.

And to be honest, the fan story that Starfleet adopted the Delta as the universal insignia for Starfleet was pretty cheesy and made the Star Trek universe smaller and the characters far too much of god figures. Besides, in TMP we see the crew of Epsilon 9 sporting unique insignia for their posting, so it’s clear that Starfleet didn’t adopt the Delta universally at that point. The theory is kind of a mandela effect.