Parameters

• Untyped Var parameters can be denoted by

    Procedure Foo ( Var x );
  

  like in Borland Pascal. In GNU Pascal, you can also use

    Procedure Foo ( Var x: Void );
  

• GNU Pascal defines "ellipsis" parameters vor variable argument lists,

    Procedure Foo ( a: Integer; ... );
  

  but does not (yet) provide a portable mechanism to access the additional arguments.
• Structured function return values: According to Extended Pascal, GNU Pascal allows structured function return values.
• Open array parameters

    Procedure Foo ( a: array of Integer );
  

  are implemented. However, Standard Pascal conformant array parameters (only partially implemented) are a "cleaner" mechanism to pass arrays of variable size.
• GNU Pascal supports Standard Pascal's procedural parameters:

    Procedure DrawGraph ( f: Function ( Real ): Real );