BFC of mirrored parts?

[Travis Cobbs]

If a file is determined to be a part, its "parent BFC" state is forced to be treated as if it were "CERTIFY", so if the part itself is certified, it doesn't matter whether its parent is certified. This is covered in the third paragraph of the Language Extension Functionality section of the BFC spec. The actual examples given there don't include uncertified mirrored parent parts, but the general wording of that paragraph does make it clear that BFC should be enabled in this case.