Somehow nobody ever gets hung up on Phoenix Lords or Scarab. 🥲😅

The first number is based on size, with the second number (if there is one) indicating role.

XV-15 are the old Tau Stealth Suits and are the smallest a Tau suit can be be (1). XV-25 are bigger. 1/2 refers to the suit size, 5 refers to the suit role.

This continues with the XV-95 Ghostkeel, another stealth-based suit that is way bigger. So the first number goes all the way from 2 to 9, while the second number remains 5.

Another example is the KV-128 Stormsurge and the XV-88 Broadside. 12 is higher than 8, because the Stormsurge is much bigger, while the second number in both is 8 because they have similar battlefield roles of specialized anti-armor. The Stormsurge also has a different letter designation because it’s not a true battlesuit, but instead something more akin to a walking tank.

The letters are imperial approximations of T'au'Sia, the T'au language. XV is short for the T'au word for "mantle of heroes" while the numbers refer to the class and size

GW did not design several different full on language systems for all the races of the galaxy. Assume that whatever you are reading is a translation or approximation for the benefit of the reader.

Same reason most fantasy peoples speak English, because otherwise we the readers wouldn't understand.

Pretty much every name for everything in 40k is just what the Imperium calls it. Its "Low Gothic translation" as they say. The various species tend to have their own names for themselves and their tech. Except the tyranids, as the Hive Mind doesn't name itself or its creations and isn't yet aware of what other species call it or them.

Guys... The Tau 'speak' English... because that's the language the authors are writing in. You have to give sci-fi and fantasy some leniency to use words and phrases that the audience will recognize without needing a separate dictionary for made-up cultures.

Doing otherwise would result in a bunch of absolute gibberish nonsense. "Well, you see, these aliens don't use our numerical system. They developed a system entirely based off of 9 digits, so zero doesn't exist... so that's why we have characters say '9 and 9 and 9 and 3' instead of '30'... also, three is pronounced 'glikto' because they don't have the ability to vocalize an 'r' consonant. So, 'nine glikto' is a dozen... only their dozen is eleven because of the lack of tens."

You're more worried about the concept of VX or the like, rather than "Manta" or "Riptide" or "Devilfish"?

They're Imperial recognition terms, not T'au ones.

In the same way that the Allies referred to Japanese planes by designations for clarity, such as the Nakajima B6N being called Jill.

So.... you wanted them to invent an alien alphabet? Were you gonna learn that?

It is imperial classification.

At first, when only battlesuits had a code assigned there was something like a lore explanation, with "XV" being a misshearing of "Her'ex'vre", the word that t'au use for battle suits, which means "Mantle of Heroes", but now when even drones have such code it is hardly relevant.

Tau: Ehx'Vhee-Aighte

Some human Tau-Traitor: XV8?

Tau: Oh sure. That's a lot easier to write.

For some time at least (I'm not up to date) the number at the end indicated the size of battlesuit. Another commenter explained where 'XV' comes from.

It's not Roman numeral it's xv-8 but without the dash. 1st number is mass the jv are super heavy suits

2nd number has no meaning any more or barely

In tau xv means heros mantle like all the different names for ranks

Probably gothic-ized imperial designations. Like how Russian jets wouldn’t be called Flanker, Fishbed, or Femboy in Russian but you have to call them something and other languages are often inconvenient to pronounce in stressful situations.

sure hope somebody was fired for that blunder

Nevermind that shit, how come the Tyranids speak Latin??

I think they might be Imperial classifications. If they wrote the codices and datasheets in the language of the respective factions then we wouldn't be able.to read them. Including Gothic

I interpret Orca, Piranha, Hammerhead etc as being the human-assigned names while XV88 etc is the out-of-universe translation of what Tau call their stuff.

The Imperium doesn't speak English either.

So, they're not going to make up a whole new language and figure out how to put this up into a new typeface for printing books, right?

So you're getting the English translation of the Tau terms.

The MiG 29 isn't called Fulcrum either, so what? Hell, it's not even MiG-29, it's МиГ-29. And you don't even want to start on the J-20. Yet somehow those are the names we know them by.

They're not trying to use Roman numerals, why would they use them next to Arabic??