Most of PMP's library units may be parametrized through conditional defines and / or conditional compilation.
The PMP's ability to pass a $DEFINED symbol with its optional value from the global project options or from the main program has been used.
If a $DEFINED symbol is not declared, the unit may use a default value.
This is very efficient, because the code is optimized at compile time, rather than passing a lot of parameters to initialization routines and generating all the code for all the cases.
A unit that strongly uses this method is the LCD unit.