root certs on smart cards

Hi folks,

I'm just now looking into smart card programming.  I wondered, is it possible 
or would it even make sense to have root certs stored on a smart card?  I ask 
because if I'm validating a certificate I wonder if my app should try to read 
some roots off of an inserted smart card, to use for validation (either in 
place of, or in addition to, the usual roots on the host system).  Note that 
I'm not talking about secondary issuers, as I know those can be on a smart 
card.

As I understand it, smart cards are basically containers for data structures 
that can perform algorithms on the types they know about.  It might be that 
any x.509 question is beyond the scope of what smart cards actually do, and 
so instead I'm supposed to follow some unwritten "best practices".  Any 
websites about this would be great.

Sorry if this is the wrong kind of mail for this list.

Thanks,
-Justin