L2C only became operational in 2014 so all current receivers are likely to be C/A code compatible. As well as selective availability there is a possibility that modern receivers would get confused when operating prior to the 1999 time roll-over. Poorly designed receivers might also get confused by leap seconds.

L2C only became operational in 2014 so all current receivers are likely to be C/A code compatible. As well as selective availability there is a possibility that modern receivers would get confused when operating prior to the 1999 GPS Time roll-over (overflow). Poorly designed receivers might also get confused by leap seconds.