It seems like such a simple thing, but I can’t seem to find it anywhere.
There’s a couple of dozen of different module types in suiteCRM, but I can’t find an explainer file that lists all of them. Not in official application guide or in source code (for example there’s nothing about “Line Items”)
Does anyone know if a complete list exists somewhere?
The best approximation is the User Guide
But not everything is there (yet), no. (You can add to that site if you like writing Docs)
Some of those are not real independent Modules. For example, Line Items are a part of the Invoices/Quotes modules.
Ask me about any others you don’t understand.
As I see it, and maybe I am wrong, Line_items are AOS_Products_Quotes in the folder structure. A relationship between AOS_Products and AOS_Quotes is many-to-many, so you should have an another table by which such relationship could be realized, AOS_Products_Quotes is such “another table”. To understand what line_items are, it is nice to look at /modules/AOS_Products_Quotes/line_items.js as well as other files at that destination.