[brandmeyer]

Hear, hear!

Galileo and BeiDou behave similarly to GPS in this respect. Oddly enough, all three time bases have an origin that is specified in UTC, but model elapsed seconds since that epoch. So GPS time does include the 9 leap seconds which occurred prior to its epoch. Galileo time's epoch is aligned to the GPS week, so it shares a leap second offset with GPS, but its still specified in terms of UTC (1999-08-21T23:47). BeiDou's epoch is specified as 2006-01-01T00:00 UTC, so it includes another 14 leap seconds with respect to GPS. So the three systems do not quite model the platonic ideal, but fortunately the offsets are all constants and its trivial for the receiver to use such an ideal in practice.

GLONASS time is UTC + three hours (ie, Moscow civil time) and does have leap seconds. To figure out the leap second offset between GLONASS time and GPS time the GLONASS ICD actually tells you to get that info from the GPS broadcast messages, although they do have an alert system for upcoming leap second updates. One more reason to dislike working with GLONASS.