mr.WHO wrote:S/M/L/XL is NOT A CLASSIFICATION in X-rebirth. It's as you said - size.
You have small freighters (M), medium freighters(L) and huge freighters (XL),
Fighters (S and M size), Corvettes and Bombers (M size), Frigates (L), destroyers and carriers (XL) - this is the actual classification of X-Rebirth, so you can easily differentiate ships of the same size.
You are too fixiated on the letters and miss the actual usage. You just want to have M0, M1...M8 because it's sounds cool....nerd

Actually, if as you say the size distinctions aren't a classification (and I don't disagree), then there is effectively NO classification, and ABSOLUTELY no abbreviated classification, which is useful in some situations. However, this is also in part due to lack of variety and distinctiveness in the ships: "fighters" - well, in previous games we had scout fighter (M5), interceptor/light fighter (M4), medium fighter (M3), heavy fighter (M3+) - these designations are NOT frivolous or gratuitous, they are in fact VERY useful - but only because there are ships of various roles to discriminate between. Now, in XR, we have "fighter" - whoop-de-****ing-do! ES can do better than that!
And as for the larger (capital-grade ships), how do we even distinguish between ship classes, seeing as there's very little of categories in the first place? There are too few ships to even really comprise actual ship classes. There's ONE missile frigate - does it get its own ship class? So what's a Stromvok? A "non-missile" frigate? What about the Suls? Oh right, those are supposedly light and medium "carriers", yet there is nothing for them to carry that can't be hosted by any other capital ship, and the same applies to the full-size "carrier". So the ship line-up in
Rebirth is too weak to merit ship classes.
Where are these "corvettes" and "bombers" you speak of? Do you refer to Katanas and Drostans, respectively, perhaps? Well, the latter perhaps can be thought of as "bombers", but certainly I haven't found anything that can reasonably be thought of as a "corvette" - the Katanas are nothing more than slightly tougher and easier-to-hit fighters.
The codified designations may appear "nerdy" and "cool sounding" (really? I personally don't think they sound cool at all, so guess again; to me they simply fulfil a function of brevity and communicative efficiency - different strokes for different folks, I guess

) (That being said, though based entirely on a spurious and unsubstantiated assumption, your guess of "nerd" IS bang-on, heheheh!) Furthermore, they enabled a VERY useful function in terms of sorting the property list by ship class -
Rebirth's property list is... ahem... "not excellent" (to put it VERY mildly!), and I think that a properly functional replacement for it (in X4) would
require a more formalised ship classification system.
Your post has drawn my attention to something: in
Rebirth, there are not enough ship types to justify a structured system of ship and ship class nomenclature, so perhaps the problem actually lies there, rather. I would be very disappointed to see even as little as triple
Rebirth's ship selection in X4 (disappointed because then I shan't be buying and playing the game) - and I don't mean only in terms of ship models, but in ship *types*. "Fighter", for example, is for me much too broad and vague a category, far too lacking in subtlety and nuances. THAT is what I'm after, not allegedly "cool" alphanumeric codes.
Lastly: OK, so S/M/L/XL is all about size - but even here the "system" is "rather broken" - the "gap" between M and L is simply too great, there is no smooth transition. Maybe you think that a smooth transition is not required, but I do. The jump from piloted boats to crewed ships is too abrupt - in fact, to refer back above somewhat, there is a hole shaped much like a corvette from "classic Xs". (Functionally, the Skunk appears to be the closest to filling that hole - but that ship is listed as being SMALL! So, we can add "inconsistent" to the adjectives for this "system".)
Happy hunting!
In other news, and completely off-topic: 12 hours now without water - "thanks", municipality! Grrrrr!