In my EAW folder there is a "DirSets" folder and this is what it contains:

There is also a "DirSetExeManager" program and if I run it it lists the files available:
If I select "ETO01" the program copies "ETO01" and pastes it in my EAW folder as "Dir.set".
From 1.28c ownards the eaw.exe will always look for a "Dir.set" file in the root folder, and use it if one is present.
So if I now run the exe it will read the "Dir.set" file and this is what it would find:
ETO_01
PIC
NULLIf I had selected "ETOBargeTrain" the loaded "Dir.set" would have read as follows:
ETO_01
PIC
Train-Barge3
NULLThe exe is asked to look for any files that it needs in the first named folder, then the subfolders. NULL is a terminator telling the exe that the list has been read. In both cases in this example the exe will look for files in the "ETO_01" folder, then the "PIC". However, in the second case the files in the "Train-Barge3" folder will also be used.
Looking at my ETO_01 folder here are the contents:

You can see the "PIC" and "Train-Barge3" folders, but there are more, some of which are automatically used.
If there is a "seasons" file the seasonal terrain is read from the folders inside it, depending on the mission date.
They are spring, summer, fall, light winter and winter.
Otherwise the default terrain is used.
There are some planesets, in this case normally four, but I have added a couple more to mine for software testing.
Because there are planesets in this folder they will be listed for selection on the 'config' screen:

I have chosen Plenest2, so looking in this folder the exe will find a number of files, including two very important ones. There is he "PDir.set" containing the paths to the skins for each of the 30 slots, and the FMDir.set" file which has the paths to the flight model data.
This is what it will read:
PLANES\SLOT00\P38H_01
PLANES\SLOT01\P38J_01
PLANES\SLOT02\P47C_01
PLANES\SLOT03\P47D_01
PLANES\SLOT04\P51B_01
PLANES\SLOT05\P51D_01
PLANES\SLOT06\B17G_01
PLANES\SLOT07\B24A_01
PLANES\SLOT08\B26A_01
PLANES\SLOT09\SpitVcLF_01
PLANES\SLOT10\SpitIXc_01
PLANES\SLOT11\SpitIXc_02
PLANES\SLOT12\Spit14e_01
PLANES\SLOT13\Typh_01
PLANES\SLOT14\Temp_01
PLANES\SLOT15\MosqFBVI_01
PLANES\SLOT16\Bf109G2_01
PLANES\SLOT17\Bf109G6_01
PLANES\SLOT18\Bf109K4_01PLANES\SLOT19\Bf109G14_01
PLANES\SLOT20\Bf110G2_01
PLANES\SLOT21\Me410_01
PLANES\SLOT22\FW190A_01
PLANES\SLOT23\FW190D9_01
PLANES\SLOT24\Me262A_01
PLANES\SLOT25\Ju88A_01
PLANES\SLOT26\Ta152H_01
PLANES\SLOT27\Ju87D_01
PLANES\SLOT28\FW190A_01
PLANES\SLOT29\V1_01
and
PLANES\SLOT00FM\P38H_FM
PLANES\SLOT01FM\P38J_FM
PLANES\SLOT02FM\P47C_FM
PLANES\SLOT03FM\P47D_FM
PLANES\SLOT04FM\P51B_FM
PLANES\SLOT05FM\P51D_FM
PLANES\SLOT06FM\B17G_FM
PLANES\SLOT07FM\B24A_FM
PLANES\SLOT08FM\B26A_FM
PLANES\SLOT09FM\SpitVcLF_FM
PLANES\SLOT10FM\SpitIXc70_FM
PLANES\SLOT11FM\SpitIXc66_FM
PLANES\SLOT12FM\Spit14e_FM
PLANES\SLOT13FM\Typh_FM
PLANES\SLOT14FM\Temp_FM
PLANES\SLOT15FM\MosqFBVI_FM
PLANES\SLOT16FM\Bf109G2_FM
PLANES\SLOT17FM\Bf109G6L_FM
PLANES\SLOT18FM\Bf109K4_FMPLANES\SLOT19FM\Bf109G14_FM
PLANES\SLOT20FM\Bf110G2_FM
PLANES\SLOT21FM\Me410B_FM
PLANES\SLOT22FM\FW190A6_FM
PLANES\SLOT23FM\FW190D9_FM
PLANES\SLOT24FM\Me262A_FM
PLANES\SLOT25FM\Ju88A4_FM
PLANES\SLOT26FM\Ta152H_FM
PLANES\SLOT27FM\Ju87D_FM
PLANES\SLOT28FM\FW190A8_FM
PLANES\SLOT29FM\V1_FM
So it will get the data from the "Planes" folder:

Using Slot18 as an example:

You can see the "Bf109K4_01" and the "Bf109K4_FM" folders which the exe has been instructed to use for that slot.
That covered just Slot18, but the same applies to the other 29 slots.
One thing that users need to be aware of, is that all versions of the eaw.exe will use a needed file if it is in the root folder as a priority, so a "PP38HF.3dz" file in the root folder would be used in reference to one in a the skin folder listed in "PDir.set".
Also, like the earlier exes, if a file cannot be found in the root folder, or any of the folders listed in the three "Dir.set" files, then the exe will look for it in the appropriate CDF file.
I hope that this gives the reader a clear picture of the current EAW system. It beats the 'you know what' out of the old system with hundreds of files being moved in and out of the EAW folder.
Jel