procedure Error(Code: ErrorSpan; Position: TextPosition);
  extern;

procedure StartError(Position: TextPosition);
  extern;

procedure PragmaticError(Code: Scalar);
  extern;

procedure SystemError(Code: Scalar);
  extern;

procedure FatalError(Code: Scalar);
  extern;

procedure NextCh;
  extern;

function LineEnded: Boolean;
  extern;

procedure InitListing;
  extern;

procedure EndListing;
  extern;