This document provides the additional interoperability requirements to allow backward compatibility between: •B2 ground systems and B1 aircraft systems; or •B2 aircraft systems and B1 ground systems. Based on a coordination plan agreed to by the Federal Aviation Administration (FAA) and Single European Sky Air Traffic Management Research Program (SESAR) dated August 7, 2013, this is an initial release of this standard. The final release will include the additional capabilities of Dynamic RNP, Advanced Flight Interval Management, and ATC winds. Note to the users of ED-228, ED-229, ED-230, ED-231: The Council noted that all above documents are labelled as ‘initial release’ and a disclaimer is included on the title page of each of the documents to explain their specific situation. Whilst the EUROCAE Council understands the reasons for these extraordinary measures, the Council would like to emphasise their exceptional nature. The EUROCAE Council notes that the term ‘final release’ in this context is to be understood as ‘next release’, and would like to stress that the documents are considered to be fully valid and applicable standards.