User-defined packed arrays of characters with specific lower and
  upper   bounds  provide  a  method  of  specifying  fixed-length
  character strings.  The string's lower bound must equal 1.   The
  upper bound establishes the fixed length of the string.

1  –  Examples

  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.