The following example shows a declaration of a character  string
  variable of twenty characters:

  VAR
     My_String : PACKED ARRAY[1..20] OF CHAR;

  Note that if the upper bound of the array exceeds 65,535, if the
  PACKED  reserved  word is not used, or if the array's components
  are not byte-sized characters, the compiler does not  treat  the
  array as a character string.