the most important files for making a new division are in
(your mod's name)\GameData\Generated\Gameplay\Decks
(your mod's name)\GameData\Localisation

Steps to making a new division:

1. Go into (your mod's name)\GameData\Generated\Gameplay\Decks and open divisions.ndf
2. Choose one of the base divisions, eg.
Descriptor_Deck_Division_GR_20_Panzer_multi
3. Download the text file editor Notepad++
4. use notepad++ (Top bar -> Search -> findInFiles) and search for all references
('Find in files' in /Generated/... , Search Descriptor_Deck_Division_GR_20_Panzer_multi)
5. clone all the references and their associated text
(Descriptor_Deck_Division_GR_20_Panzer_multi and everything between it and the next entry)

You do not need to clone the entry in Decks.ndf. This defines the deck given when you "Generate prebuilt deck" in the deck editor. the division will be buildable and playable without it.

6. rename all the cloned references
(Descriptor_Deck_Division_GR_20_Panzer_multi -> Descriptor_Deck_Division_New_Division_multi )

7 if you want to deal with decks.ndf

export Descriptor_DeckGenerated_New_Division_multi is TDeckDescriptor <-THIS NAME IS UNIQUE TO THIS FILE
(
DeckNameAsString = 'New division'
DeckDivision = ~/Descriptor_Deck_Division_New_Division_multi <-THIS IS THE SAME AS IN OTHER FILES
IncomeByPhaseIndex = 0
DeckPackList =
[
TDeckPackDescription
(
Quantity = 1 <-# of packs
AvailableFromPhase = 2 <- 1=B 2=C. delete this line for A phase
ExperienceLevel = 1 <- 1=Vet1 2=Vet2. delete this line for 0vet
DeckPack = ~/Descriptor_Deck_Pack_
),
At the bottom of the file in the
private DeckList is TDeckDescriptorList
(
DeckListForAutoFill =
[
~/Descriptor_DeckGenerated_New_Division_multi, <add your deck you defined at the top of the list, the one unique to this file


8. Create a new packs (run search and replace all references just like with Descriptor_Deck_Division_GR_20_Panzer_multi) or choose pre made packs with the units you want to add to your division from packs.ndf
9. in Divisions.ndf replace the packs already there with the packs you chose in step 6
10. in Divisionrules.ndf add rules for all the units in the packs that you added
11. clone a divisioncostmatrix in divisioncostmatrix.ndf and give it a new name
12. replace the original costmatrix in divisions.ndf with the one you just made

11. in MODDING.csv create new text strings (clone the template and replace TOKEN with a custom string that is 1-10 characters long, and relpace REFTEXT with the text you want to show up in game
12. replace:
DivisionName = 'Div_20Pz'
DivisionNickname = 'SNGR20Pz'
DivisionDescription = 'DESGR20Pz'
with the tokens you just created.

Click the "Generate mod.bat" in the mod's folder


--- IMPORTANT ---
If you clone anything with a GUID, eg. DescriptorId = GUID:{9c32d848-0825-4e85-8535-0dcd53e79193}, you need to replace the GUID with a new unique GUID
You can generate them by going to https://www.guidgenerator.com/online-guid-generator.aspx
There are GUIDs in Packs and Descriptor_Deck_Division.
Many other templates have them, but the above 2 are the only ones you need to know about to create a new division with existing units.




While not complete, here is a guide on how infantry squads are coded
https://docs.google.com/document/d/1Xu23UgjpzDDtX6_wWyG6ApjqSNplo8pryI52ZjAggMo/edit?usp=sharing

Image in doc has bad quality so here it is again: