predecessor-set and successor-set properties

Hi,

The latter is defined in terms of the former, making them
computed and protected respectively. This suggests an
implementation. I think both should be protected and have
a stand-alone definition.

Regards,

Werner.
-- 
Werner Donné  --  Re
Engelbeekstraat 8
B-3300 Tienen
tel: (+32) 486 425803	e-mail: werner.donne@re.be