4.7.1.3.2 XC8 Linker - Memory model options

Size of double
This selector indicates the size of the double type. Currently, only 32-bit floating-point types are permitted.
Size of floats
This selector indicates the size of the float type. Currently, only 32-bit floating-point types are permitted.
External memory
This selector controls how external memory is accessed. See Emi Option.
RAM ranges
This field adjusts the data memory used by the program. See Ram Option.
ROM ranges
This field adjusts the program memory used by the program. See Rom Option.