Ncpos (string, substring)
Ncpos (string, substring, n)

   Synopsis:
      Returns the position in the string of the first occurence of any character
         that is NOT in the substring

   Notes:
      (Axbasic labels the first character in the string as 1, the second as 2,
         and so on.)
      If all of the characters in the substring occur in the string, 0 is
         returned. If the string is an empty string, 0 is returned. If the
         substring is an empty string but the string isn't, 1 is returned.
      If the third argument is specified, the search begins at the nth character
         in the string and proceeds to the right. Ncpos (string, substring, 1)
         is interchangeable with Ncpos (string, substring). If the substring is
         empty but the string isn't, the starting position is returned.
      If n is not an integer, it is rounded off. An error occurs if n is zero or
         a negative number.
