Software implementig Hierarchical trust

[Salvatore Nesta <s.nesta@xxxxxxxxxxxxxxxxxx>]

Hello,
in the new draft:

>INTERNET-DRAFT                                         Lutz Donnerhacke
>Security                                               IN-Root-CA
>Expires in six months                                  Individual Network e.V.
                                                       October 19 1997

 >                       PGP Message Exchange Formats
 >                     <draft-ietf-pgp-formats01.txt>
Lutz Donnerhacke writes:
>....
>There are two models of key management: Hierarchical trust and Web of trust.
>...
>Existing software implement the Web of trust...

So, the question is:
Existing software implement the Hierarchical trust? And, if not, why?

Thanks

		Salvatore Nesta
		s.nesta@xxxxxxxxxxxxxxxxxx