The OASIS AS4 standard is referenced in EU legislation, as communication protocol supporting interoperability and data exchange for transmission operators for gas, according to article 21 of:
http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=uriserv:OJ.L_.2015.113.01.0013.01.ENG Some quotes below. Kind Regards, Pim The common data exchange solutions shall comprise the protocol, the data format and the 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. This Regulation shall enter into force on the twentieth day following that of its publication in the Official Journal of the European Union. It shall apply from 1 May 2016 without prejudice to Article 5. This Regulation shall be binding in its entirety and directly applicable in all Member States. Done at Brussels, 30 April 2015. For the Commission The President Jean-Claude JUNCKER