The  STRING  predefined  schema  provides  a  way  of  declaring
  variable-length  character  strings.  The compiler stores STRING
  data  as  though  it  were  stored  in  the   following   schema
  definition:

  TYPE
     STRING ( Capacity : INTEGER ) = VARYING[Capacity] OF CHAR;

  The syntax of the discriminated schema is as follows:

     STRING ( Capacity )

  The 'Capacity'  is  an  integer  in  the  range  1..65,535  that
  indicates the length of the longest possible string.

  To use the predefined STRING schema, you provide an upper  bound
  as the actual discriminant.  Consider the following example:

  VAR
     Short_String : STRING( 5 );    {Maximum length of 5 characters}
     Long_String  : STRING( 100 );  {Maximum length of 100 characters}

  You can assign string constants to STRING variables from  length
  0  to  the specified upper bound.  The compiler allocates enough
  storage space to hold a string of the maximum length.  A  STRING
  variable  with  length 0 is the empty string ('').  You can only
  use character-string constants (or expressions that evaluate  to
  character strings) to assign values to variables of these types;
  you cannot use standard array constructors.

  You can access the CAPACITY predeclared identifier as you  would
  a  schema  discriminant,  and you can access the LENGTH and BODY
  predeclared identifiers as you would access fields of a  record.
  The   CAPACITY  identifier  allows  you  to  access  the  actual
  discriminant of the STRING schema; the LENGTH identifier  allows
  you  to  access the current length of the string object; and the
  BODY identifier contains the current  string  object,  including
  whatever  is  in  memory up to the capacity of the discriminated
  schema.