IMPLICIT_NONE

 Disables the implicit declaration of data types in the program
 unit.  When it is used, you must declare the data types of all
 symbols explicitly.  You must not include any other IMPLICIT
 statements in the program unit containing an IMPLICIT NONE
 statement.  Statement format:

    IMPLICIT NONE

                                NOTE

         To receive diagnostic messages when  variables  are
         used   but   not  declared,  you  can  specify  the
         /WARNINGS=DECLARATIONS compiler option  instead  of
         IMPLICIT NONE.