Copy function

  DECLARATION:  Copy(S : String; Index : Integer; Count : Integer)

      PURPOSE:  Returns the substring of a string

         UNIT:  System

  RESULT TYPE:  String

      REMARKS:  Where S is a string-type expression and Index and
                Count are integers.  This will return a string containing
                Count characters starting from the Indexth character in s.
                If Index is larger than the length of S, an empty string
                is returned.  If Count specifies more characters than remain,
                in S, only the remainder of S is returned.

      EXAMPLE:  Var
                   S    : String[25];
                   Sub1 : String[10];
                   Sub2 : String[5];

                Begin
                   S := 'This is a complete string';
                   Sub1 := Copy(S,1,7);
                   Sub2 := Copy(S,6,2);
                   Writeln(S);
                   Writeln(Sub1);         { 'This is' }
                   Writeln(Sub2);         { 'is' }
                End.