This check box controls whether parentheses are mandatory in all function and procedure calls and after the program name. In Pascal parentheses are not normally used when calling or declaring functions or procedures with no parameters. So for example in the following statement:
a := b;
it is not clear whether b is a function that takes no parameters or whether b is a variable. When mandatory parentheses mode is enabled then parentheses are required when declaring or calling all functions and procedures even those with no parameters. Parentheses are also required after the program name even if there are no program parameters.