AS4 is selected as communication protocol in  network code on interoperability and data exchange rules for natural gas transmission network:

The following common data exchange solutions shall be used for each of the types of data exchange listed in paragraph 1:

(a)

For the document-based data exchange:

(i)

protocol: AS4;

(ii)

data format: Edig@s-XML, or an equivalent data format ensuring identical degree of interoperability. Entsog shall publish such an equivalent data format.