What should i do with this: (from Xerxes _ Achaemid Empire)

<ArtDefineTag>ART_DEF_CIVILIZATION_Achaemenid_Empire</ArtDefineTag>
<ArtStyleType>ARTSTYLE_MIDDLE_EAST</ArtStyleType>
<ArtStylePrefix>AFRICAN</ArtStylePrefix>
<ArtStyleSuffix>_MIDEAST</ArtStyleSuffix>

to get that applying the ED Persia units?

Change
to

Oh, that's all? I was unsure as for prefix African, if this line needs also something.

Last question to this civ: Are "_Persia" ED units more covered compared to _Mideast? (or equal). And i would like to make sure, that no african skins are applied for this civ.

Important for everything:
I apply the era mod "Eras - Classical Age (v 33)" (which means, i play from Ancient to Classic era alone (but on Marathon speed edited, so i have even more turns vs the default mod settings/calculations).
-> So when i ask about ED units, i speak solely of Ancient and Classical era units.

To answer my question above, _Mideast seems to be more covered vs _Persia (judging from 1-JEDUnitGraphicConfig.sql). So i let the Achaemids with _Mideast.

Actually, the logic that's applied is more complicated. Persia will automatically use Mideast if there isn't a specific one assigned (see 1-ArtStyleConfig.sql for these assignments). You can also specify a different fallback override for a particular unit by putting a different suffix in the fallback column of the 1-JEDUnitGraphicConfig.sql file.

This comment is again pretty helpful, as it confirms what i recently only assumed. Thanks!
Yes, in this case _Persia should go.

P.S. Is there somewhere a source (or kind of tutorial) for the .spl tables, ie. exact definitions for its columns?
Example, iirc. some units have 4 column definitions (art suffixes), what exactly is doing what, or why have some of them 4, others only 2. Of course i got it, that the main-entry is "ArtStyleSuffix" which is in the sql's after the civ the second column.

The file doesn't actually directly correspond to one specific table in the game, but the SQL translates this table to fill in various tables.

All the data is in a Microsoft Excel file on the GitHub < https://github.com/Nutzzz/Civ5-EthnicDiversity >. I wrote some macros that automatically generate SQL for ArtStyleConfig and all the different scaling options of UnitGraphicConfig. The cells with little red triangles in the corners have comments associated with them.

But here's a quick rundown:
Columns: Suffix, Fallback, Template, Member, MemSuffix, fxsxml, Num, Scale, Form

Suffix = An ArtDefineSuffix we've been discussing above
Fallback = An alternative ArtDefineSuffix to use. [Sorry, I had forgotten, but actually the Fallback (2nd) column doesn't actually do anything by the time it ends up in the SQL (it used to, but rather than having the game do all the processing every time you activated the mod, it was faster to have it preprocessed by the Excel macros--so it's only informational at this point to remind me where the data came from).]
Template = ART_DEF_UNIT_xxx (the unit, usually composed of multiple models)
Member = ART_DEF_UNIT_MEMBER_xxx (the specific model within that unit)
MemSuffix = ART_DEF_UNIT_MEMBER_{Member}_xxx (for units comprised of different models).
fxsxml = a filename describing the actual art to use
Num = number of this unit member in the model (note the same MemSuffix/fxsxml often appears multiple times in the same unit, to help mix up the models within a unit better).
Scale = size of the unit
Form = formation; the first one in a particular template unit grouping is the only one that controls.

Thanks!
I wonder if one should/could use then '_GREECE' instead of '_MED' for Greek mod-civs as Suffix. Required, one plays with mod-only civs (via according mod, which disables all vanilla civs)?

You certainly could if you wanted. Though why does it matter whether you're playing with mod-only civs or not?

I thought if vanilla civs are present, then the vanilla Greece civ would interfer with the Suffixes?
Related:
I'm still a bit confused (but i didn't watch now into the sqpl's, it's from last memory): _MED Suffix units are not the same for Greek mod civs as _GREECE Suffix units, or? ED unit fire-wise meant, of course.
I'm just still under the impression, that _GREECE is done for the vanilla Greece civ, and thus a lot units are covered for them, but not necessarily for _MED, or here Greek mod-civs?

No, there's nothing magic about the "_GREECE" suffix that relates to CIVILIZATION_GREECE; just as multiple civs could have _ASIA or _AFRI, multiple civs can have _GREECE at the same time (and at the same time as CIVILIZATION_GREECE) with no ill effects.

Just as _PERSIA uses _MIDEAST if a specific unit has not been assigned, _GREECE uses _MED, so there's a bit of overlap, but Greece is fairly well-covered compared to some civs, so it doesn't need too many. _MED is a tough one to allocate units for a "generic" Mediterranean since it covers such a wide area, even if you constrain it to the Northern area between, say, Portugal and Greece. A lot of the units assigned to _MED were designed for Spain, so some of the uniforms give a bit of the North African flavor from the time of the Moorish conquests, but you may or may not feel that's appropriate for your purposes.

I'm guessing the only reason some mods you found are using _GREECE vs. _MED is that _MED is one of the "built-in" suffixes that vanilla civs/CSs were given, but it's never actually used for anything in the vanilla game (unlike the building and music styles), and those civs/CSs end up using the default EURO settler. So if a mod civ uses _GREECE as the suffix to support the ethnic mods instead of _MED, it doesn't really hurt anything. An Asian civ mod wouldn't have that luxury, and would need some kind of SQL like that posted in the original post above.

You are certainly welcome to make suggestions about how the units are allocated. Most of the choices are originally Gedemon's from R.E.D. Modpack, but given the required trade-offs of balancing everything, I have personally found the vast majority of the choices he made were well done.

Understood. And agreed, that the choices are well done (without knowing too much of it, just an impression as of yet).
Atm., and i guess that will remain*, i'm only interested in ancient and classical era units.

* because when i'm done with my scenario modding and playing it enough, i'll go back to other games, seeing how much work it means for me to make Civ 5 fitting for my game preferences ;) ... Civ 5 has generally a great game concept, like it a lot, but the rush through the periods "destroys" it for me, as i cannot bear the quasi drastic unrealism with pretty much every step forward (i'm just a history buff). Thus, i try to realise my Ancient/Classical Greek story of the game, and i'm nearly ready (as said, the vanilla/DLC game files are edited, and nearly all used mod files as well). Small examples: No elephants (ivory), no cows, no bison, some resources renamed when the picture fits example cotton is olives, silk is linen, sugar is herbs and such more, many units replaced (example archer replaced with slinger, composite-archer is replaced with peltasts) and buildings replaced and such things more like also no citadel and all religion items fitting to the time and area.

As for _GREECE or _MED, because the change is possible on-fly, i'll decide when i saw the _MED units in-game. And thanks again for your time, you are doing a great "job" here!

Btw., Civ 5 is the only Steam-game which i play Steam-online (Witcher 3 is still an exception, while majorily played Steam-offline as well), because i must so often watch and act here in the Civ 5 workshop (grab mods etc.), lol.

Strange things experienced: I tried in the meantime _GREECE for iirc. 18 of the 22 setup mod-civs (former _MED suffix), within AM, AMC, MC Gr.split, Thebes, DMS Epirus.
AM and AMC apply from up Warrior (the Spanish model, i assume), also saw a different Archer model (no idea what happens from up Spearmen). MC split and Thebes do not apply the ED Warrior, but vanilla. But apply ED Archer (it's the same as they had have with _MED). According Epirus units not seen as of yet.

These latter civs which don't get the same _GREECE units come btw. with unit models on board. Can this be a reason to exclude certain ED units?

And, all these latter had default unit compatibilty sql's _GREECE else _MED (was done for EU/RED). As i found they don't fire accordingly, i disabled these sql's (as AM and AMC do not have these sql's i thought it would make sense), but that makes no difference for the output. That puzzles me ... .
I'll try to assign additionally a Warrior alternative for _GREECE; as _MED has several of them (the Spanish), but seem not to fire for all mod civs.

Btw., i have also applied _PERSIA for Achaemids, _CARTHAGE for MC_Minoa, _SPAIN for Illyria from AM (then i have still Dacia from AM, used as Pannonians, but left so far iirc. with their default mod setting). All these latter ones, the according units, i didn't see as of yet.

Is this interesting, or boring for you? (lol) ... i guess, it's boring because you know what sticks behind it?