So, I know this isn't what you're expecting, but entertain me here for moment.

There's a new game that recently released titled "The Dark Pictures Anthology: Man of Medan". It's a decision making horror themed game that tells a story based on the curse or the SS Ourang Medan, which is a real ship that met a mysterious fate. More information linked here: https://en.m.wikipedia.org/wiki/Ourang_Medan

There are letters and books in this game you can read that give insight to the lore of what happened to the original crew of the military vessel. On some of the letters you find, the soldiers are writing back to their families. On these letters, there are numbers printed onto them which are followed by a series of letters. They are as follows;

5/12 - tse

5-17 - xzf

They are not written by hand like the rest of the letter, they're clearly made by a typewriter. The numbers are presumably dates, but I've no idea what the letters following them mean. I've tried researching this but I don't know what to type into Google to yield the results I want, I just keep finding pages regarding service numbers and the phonetic alphabet.

My question to you guys is, are you aware of this being a real thing done by the military? If so, can you explain to me why or link me to an article that does explain it?

The reason I'm asking is, there is a part where you use a radio later in the game. When you're searching for military bandwidth, you stop on a numbers radio. I'm trying to figure out if these examples I've found are two pieces of a cipher that can be put together in order to translate the hidden message on the numbers radio.

Anyway, thanks for any that read or share this and further thanks to any that respond with any information. My apologies if this doesn't technically belong here.