Return_Value

   An integer value representing the offset of the substring
   argument. An offset is the position of a character or a substring
   relative to the beginning of the string. The first character in
   a string is always offset position 0 from the beginning of the
   string (which always begins at the leftmost character).
   If the substring is not found, the F$LOCATE function returns
   an offset of the last character in the character string plus 1.
   (This equals the length of the string.)