Fill the greek ref tables

[AVPavel]

Fills in the Greek reference tables, which were largely TBD, by documenting what the Middleware actually implements.

Article references follow ν. 5144/2024, which renumbered the articles of the former ν. 2859/2000. The myDATA category numbers themselves did not change.

What changed

ftChargeItemCase — nature of VAT (NN)

The table was TBD. It now lists every supported nature with the myDATA vatExemptionCategory it produces, so an integrator can pick the right value without reading the Middleware source. Also notes that natures 31, 36, 41 and 42 are ΦΠΑ εμπεριεχόμενος — VAT included in the price rather than absent — and points to the override channel for the three myDATA codes that have no nature value.

ftReceiptCase

Adds the missing 0400 HasTransportInformation flag. It is required together with Delivery Note (0005) to produce a myDATA 9.3 delivery note.

ftSignatureType — SignatureCase (sss)

Was TBD. Now documents the Greek signature cases, including the ones needed to read a response: MARK, UID, authentication code, QR code and the unique document identifier.

ftPayItemCase

Documents the reserved xx segment and removes a duplicated "v - version" heading.

ftState, ftJournalType, ftSignatureFormat

Replaces TBD placeholders with explicit statements that Greece defines no values of its own, so a reader can stop looking rather than assume the page is unfinished.

General reference tables

Fills the two empty Greek sections — SignatureCase and JournalCase.