The R&RNAV proposed contribution to SEASOLAS spans user requirements, use cases and scenarios, complementary technologies, the concept of EGNOS-based ‘integrity at user level’ and two cost benefit analyses (from the point of view of the user and the maritime authority).  The Analysis will form a key part of the EC determination of the maritime use of EGNOS and whether the existing definition of Version 3 needs to be revised to satisfy maritime requirements.