XML Schema (XSD)

Definition

A formal definition of allowed XML structure and data types.

Used for syntax validation (XSD validation).

Business rules go beyond XSD and check semantic constraints.

Process of checking an e-invoice against syntax rules and business rules.

Text-based markup format used to represent structured data in many e-invoice syntaxes.

Universal Business Language: an XML library for standard business documents.

UN/CEFACT Cross Industry Invoice: an XML syntax used for e-invoices.