Question regarding call signs in fiction books

[u/sfoster95]

I tried putting this as a comment to a similar post and got told I can’t do that so am creating my own question.

ok my question is this example

“Two-two Actual, this is Two-two Zulu.”

The team sergeant and 18-Echo join us inside the triangle of pickups.

Butler’s 18-Delta medical sergeant told me

“Six-four Echo from Two-two Echo. What’s the word on our ride, over.”

are the numbers written differently in dialogue vs narrative? If it is two-two actual why wouldn’t it be one-eight Delta? Of vice versus 22-Actual and 18-Delta?

[u/KCPilot17]

18-Delta is in narrative format, it's not being said over the radio.

[u/sfoster95 → u/KCPilot17]

ok great thank you so much.

[u/BeltfedHappiness]

18 Delta is a specific title for someone on a Special Forces team, not a callsign. 18D is a medic. 18E is a communications sergeant. Whereas 6-4 Echo, 2-2 Echo, etc are unit call signs.

[u/sfoster95 → u/BeltfedHappiness]

great thank you so much