I suggest that you read the introductory pages to SD-5 where it
discusses the differences between the processes of naming, registration,
and listings.
CAs are about registration as they assert some binding between names and
entities.
Directories are about listings as they publish information about names.
Directories don't care about bindings. They view names as opaque.
I can call up the phone company in +1-617 and tell them that I want a
listing for BBN and they'll give me one as soon as the check clears.
That's because they are publishing a directory, they aren't acting as a
registry.
/mtr