In Europe Passenger Name Record (PNR) data exchange is regulated to support prevention, detection, investigation and prosecution of terrorist offences and serious crime.  Annex 2 of the recent  COMMISSION IMPLEMENTING DECISION (EU) 2017/759 of 28 April 2017, which specifies the common protocols and data formats to be used by air carriers when transferring PNR data to Passenger Information Units,  mandates the OASIS AS4 standard as one of three allowed protocols for transmission protocols for the transfer of data.  

An implementing decision is establishes how a (previously legislated, technology neutral) regulation is to be used, providing a further level of detail supporting interoperability. The decision notes that "the European Commission currently promotes the use of ‘AS4’ protocol, notably in the framework of the Connecting Europe Facility (CEF)".