The standard for GNSS time transfer was first defined in 1984, associated to the use of GPS signals, which were at that time degraded by the Selective Availability. It was updated at a few instances to follow the evolution of GPS, of the receivers, and the inclusion of GLONASS. With the emergence of additional navigation systems like Galileo, BeiDou, QZSS, the standard has to be further adapted. This paper prepared by the CCTF Working Group on GNSS Time Transfer details the associated extended standard, named CGGTTS for Common GNSS Generic Time Transfer Standard, and the corresponding Version 2E of the format.Full paperThe full paper is available online at: http://metrologia.bipm.org/guides-stds-conventions/2015/G1.pdf