EN 16931 as Dart objects, the two syntaxes that carry it, and one package per national or
sector profile, so you depend only on the rules you are claiming.
Dart e-invoicing, the EN 16931 semantic model
The norm as Dart objects. Builds and checks the semantic model, syntax aside.
Dart e-invoicing, UBL 2.1 syntax
Reads and writes the invoice as UBL 2.1, the syntax Peppol and most of Europe use.
Dart e-invoicing, UN/CEFACT CII syntax
Reads and writes the invoice as UN/CEFACT CII, the syntax France and Germany use.
Dart e-invoicing, Peppol BIS Billing 3.0
The Peppol BIS Billing 3.0 profile: its identifiers and the rules it adds.
Dart e-invoicing, Factur-X
The Factur-X profile: its five levels and what each one asks for.
Dart e-invoicing, XRechnung
The XRechnung profile, and the rules Germany adds on top of the norm.
Dart e-invoicing, UBL.BE
The UBL.BE profile, and the rules Belgium adds on top of the norm.