New RINEX GNSS data format standard to be voted and approved in the SC-104 teleconference, after the IGS Governing Board approved it and adopted it last month. This new format extends RINEX to support the new CNAV-x navigation messages from the different constellations, introduces system wide messages and future-proofs the format for upcoming navigation message changes, therefore Navigation files are not backwards compatible to the previous RINEX formats.
RINEX 4.00 Observation and Meteorological files remain backwards compatible to the RINEX 3.0X format, only small changes and extensions have been added in the RINEX 4.00 Observation and Meteo formats.