This is true

EDi self isn't difficult, in a layman term it's a structure that eveyone agreed which carries business data to receipient.

There are other structures being used in industries as well, such as ANSI 12. SAP has a similar technology, called IDoc (Intermediate document). EDI can be used between any two systems provided they can be set up to send/receive it, while IDoc can only be used between two SAP systems. If a SAP system need to communicate with a non-SAP system, IDoc needs to be dropped into EDI, so the real communication is using generic EDI format.

I have experience on both IDoc and EDI, I'd say reading books is a good starting point, probably isn't sufficient to get job done.