Provide a list of content-types for the different APIs and documents

[stigbd]

We need to provide a list of content-types for the different APIs so that we are able to provide some validation on the request.

The content-types does not exist, but we can base it on document types. (Who is in possession of the document types overview?)

[ekoskent]

In PEPPOL the document type is described with documentIdentifier, see "ICT-Transport-SMP_Service_Specification-110.pdf" in https://peppol.eu/downloads/the-peppol-edelivery-network-specifications/.
"This scheme is based on a concatenation of the document namespace, root element, and optional (and
document-dependent) subtype:
{rootNamespace}::{documentElementLocalName}[##{Subtype identifier}].
Where ‗[ ]‘ denotes an optional part of the identifier, and everything outside ‗{ }‘ are string literals.
For example, in the case of a NES-UBL order, this document can then be identified by
 Root namespace: urn:oasis:names:specification:ubl:schema:xsd:Order-2
 Document element local name: Order
 Subtype identifier: UBL-2.0 (since several versions of the Order schema may use the same
namespace + document element name)
The document type identifier will then be:
urn:oasis:names:specification:ubl:schema:xsd:Order-2::Order##UBL-2.0"

For the reference implementation the supported identifiers are (at the moment):

Invoices (only UBL as the finnish ones don't have a namespace so they are tricky to define):
urn:oasis:names:specification:ubl:schema:xsd:Invoice-2::Invoice##UBL-2.1

Bank statements:
urn:iso:std:iso:20022:tech:xsd:camt.053.001.02:BkToCstmrStmt##1.4

Other vouchers to be added later

PEPPOL list of document identifiers: https://peppol.eu/wp-content/uploads/2017/12/PEPPOL_Policy-for-use-of-identifiers-300-11_certificates.pdf chapter 5.2

[ekoskent]

The API and also our reference implementation should be able to handle pdf vouchers as well, should we define a general documentIdentifier for pdf vouchers?

[ekoskent]

The API needs to have a field for the company identifier to know who's data we are dealing with. i suggest we use identifiers according to the ISO-6523-1. In consists of a country identifier + numeric part of the VAT identifier.
Example of a Finnish VAT identifier: FI12345671, Finnish country identifier: 0037

ISO-6523-1 identifier is 003712345671. There is also 5 additional digits in the end to identify a specific division etc. within one company.