pkinit slotid=N ?

[Jim Rees]

The problem with using slot labels is that some devices will have multiple
slots all with the same label but different IDs.  OpenSC does this for
example.  The only way to distinguish them is by slotid.  Same is true of
token labels.  Also, I'm not sure labels are required by pkcs11, but IDs
are.

What it really comes down to is that I've seen the spec violated by several
implementations in very creative ways, and I thought it best to have as many
different ways to identify objects as possible.  Maybe this should be
documented.