[Zope] how to import .zexp containing obsolete products???

[Gilles]

Hello

I would like to import very old exported zope file (.bbe or .zexp).
( Note: I know how to convert the zodb2 to zodb3...)

Unfortunately theses file contains products which are not installed anymore
now: old db adaptor,confera... and the import failed.

This is not really nice. Is there a way to do the import anyway? not
importing the unknown or broken objects?? Or to 'clean' the old .bbe/.zexp
from thoses objects?

Thanks

Gilles