An electronic invoice format, defined in Mexico's Federal Fiscal Code (CFF), that contains both the supplier signature and a PCCFDI (Proveedor de Certificación de CFDI) signature, along with the transaction information. Sovos supports CFDI 4.0, and you can find the corresponding technical specifications, schemas, guidelines, and catalogs on the SAT website. An important document is the so-called Anexo 20, which is the main technical specification. In the Mexico e-invoicing guide, the term CFDI refers to the supported version (4.0) — unless otherwise noted.