which usercertificate attribute

Hi,

When I use Netscape Communicator as a mail client, I can 'get' the certificates 
of my correspondents from a ldap directory.
Netscape however looks for a userSMIMEcertificate instead of a userCertificate.

Which is the correct attribute to publish Certificates in ?
I would think that using 1 certificate for all applications would be a lot more 
user friendly.

I only have one physical passport, why would I need several digital one's ?

Thierry
eMail : thierry(_dot_)vandoninck(_at_)dexia(_dot_)be