What Happens when the Code is Compiled

Only code relevant to the GUI environments specified in the GUI Targets field (plus all common code) will be compiled. If you do not list any GUI specifiers in the GUI Targets field, all code will be compiled; at runtime, code not relevant to the platform the application is running on will be skipped.

The constants you have defined are evaluated and used to compile the code. You can use this feature to conditionally load include files.