create and open function

["Antoine JORGE RIBEIRO" <softst1@bruker.fr>]

Hi!

I would like to know what is the meaning of the fourth paramtre in the
functions Create and Open from the packages Direct_IO, Sequential_IO or
Text_IO.

theses functions are described in Ada 95 Reference Manual :
(6)          procedure Create(File : in out File_Type;
                           Mode : in File_Mode := Out_File;
                           Name : in String := "";
                           Form : in String := "");
(7)          procedure Open  (File : in out File_Type;
                           Mode : in File_Mode;
                           Name : in String;
                           Form : in String := "");

if someone can explain it to me, that would be grate.
thanks

Antoine