Here you can find the guideline and technical specifications for ESAP 9.1, Periodic invoicing.
The guideline describes how the business documents are used in the business process.
The Business document specification (BDS) describes what information should be included in the electronic business documents sent between the business systems. The summary describes the structure in the business document in a clear way.
The Message specifications (MS) define how the elements of the business documents are placed in an EDIFACT message.
The Corrections are valid from that they are published and should be read together with the specifications.
The Change History describes the changes made in the published versions of the business document and mapping specifications compared to the previous version.
The specifications are write-protected, but the editable copies can be used for your own notes.