SUBSTR

 The SUBSTR function returns a substring (from a string specified
 as  a  parameter)  that  is  of the specified starting point and
 length.  The return value is compatible with  all  other  string
 types.


 Syntax:

    SUBSTR( str,start [,length] )


 The parameter 'str' is a character string value;  the  parameter
 'start' is an integer value that indicates the starting position
 of the substring.  The parameter 'length' is  an  integer  value
 that  indicates  the  length  of the substring.  If the 'length'
 argument is omitted, the length is computed to be the  remainder
 of  the  string  value  beginning at the starting position.  The
 'length' argument cannot be omitted on OpenVMS VAX systems.  For
 example,


    SUBSTR(string,start_index)

 is identical to

    SUBSTR(string,start_index,length(string)-string_index+1)


 When you use the SUBSTR function,  the  value  of  the  starting
 position must be greater than 0, the value of the length must be
 greater than or equal to 0, and there must be enough  characters
 following  the starting position to construct a substring of the
 specified length.