Signature has algorithms

[Topas]

David Shaw wrote:

>The procedure you give above will put new self signatures on the key.
>You can't recreate old ones, but you can delete them.  Note that if
>you have your key on a keyserver, the old self-sigs will come back
>since the keyserver (or really anyone else who has a copy of your
>current key) doesn't delete the old self-sigs.
>  
>
Oh I forogt a little detail,.. =)
It was clear to me that I get new selfsigs on the primarykey/userid when 
changin settings (like prefered algorithms, etc.) and it is also clear 
to me that the older selfsigs will return from the keyserver (but they 
should be ignored by other users due to the older creation time).

Was I wanted to know was: How can I get new subkey binding sigs for my 
subkey (new: with more recent creation time, and of course with the 
"better" hash algorithm)?

It would be better to wait with doing this until gpg understands 
backsigs, right?

btw: Do encryption keys get backsigs, too? If not why not?

Best wishes,
Topas.