At 02:12 07 February 2019, Andy Blackburn wrote:
Our very own Y2K bug. To be fair, they designed it before 2000 made us
all
worry about such things, but still, maybe they could've allocated an
extra
hex character.

9B

It is just transmissions on the L1 frequency that have this limitation.
Transmissions on L2 & L5 do not, but GPS Engines in Flight Recorders use
L1,
presumably on cost grounds.