Clarification, RE: IFS directory visibility from FTP

Actually, I'm not all that concerned with restricting users with "any
arbitrary" FTP client from even seeing things they don't have access to;
I'm more interested in restricting users within *our* FTP client from
seeing things they don't have access to.

In the QSYS file system, we have a different way to get a list of
libraries the user can access, and so only those libraries show up in the
GUI. But is there something I can set within an FTP session to hide such
files and directories, or some simple, quickly executed command I can
issue programmatically through an FTP connection, that would allow me to
detect a lack of authority and suppress the obect from appearing in the
list?

--
JHHL