Surface Symbol Type
The surface symbol type is used to store the reference number of a surface. If the surface's value
is passed from a JKL, any messages generated by the surface will be received by the cog. Syntax:
surface surf1 local
Or if the surface's value is passed from a JKL, don't use the local extension:
surface surf1
Mask Info: Surfaces can send two messages: entered and crossed. Giving the surface
Mask Flags
controls what things can generate these messages.