VLANs, untagged frames and (i)pf

[Edgar Fuß <efnbl07%bn2.maus.net@localhost>]

I assume these are quite trivial questions, but I couldn't find them answered 
in any docs. If I missed something, a pointer to a suitable doc would be 
appreciated.

If I have a vlan attached to a physical interface, am I right to assume that 
untagged frames will be received on the physical interface and tagged ones with 
an unassigned tag (i.e. one different from all those for which pseudo 
interfaces have been assigned) will be dropped?

Now, what about (i)pf on the pseudo and the physical interface? Will tagged 
frames be "seen" by the filter as travelling through the physical interface or 
will they only be dealt with on the pseudo one?