NANU Alerts GPS Users to Start of L2C/L5 CNAV Messages
GPS Block IIR-M and IIF satellites began transmitting CNAV messages on the L2C and L5 signals, on Monday (April 28, 2014).
In a Notice Advisory to NAVSTAR Users (NANU), Air Force Space Command announced that it would begin implementing the civil navigation Message Types (MTs) 10 and 11 (with satellite ephemerides), 30 (satellite clock data, and corrections for ionospheric and group delay), and 33 (parameters related to correlating coordinated universal time (UTC-USNO) time with GPS system time). MT12 (reduced almanac) will not be broadcast at this time.
By Inside GNSS