That was my understanding too, originally. But in the manual it says:
It is important to note that the longitude standard used in the
LX200 starts at 0 degrees in Greenwich U.K. and increases
Westerly only to 359 degrees 59 minutes. Many maps will show
Easterly longitudes which cannot be entered into the keypad
display. As an example, if your map indicates that you are at an
Easterly longitude of 18 degrees 27 minutes, then you would
enter 341 degrees 33 minutes.