This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
It is not clear how namespace resolution takes place for the selector fragments. The language here is also confusing, what is a fictional selector?
This has been addressed, hopefully: https://dvcs.w3.org/hg/webcomponents/raw-file/434441b2d90e/spec/shadow/index.html#satisfying-matching-criteria