What this is, and what it is not
These are publishing controls: they decide who can reach a publication and what a reader is allowed to do with it. They are the right tool for material that is confidential in the everyday business sense — a proposal, a client presentation, an unreleased range.
They are not a compliance product, and we do not describe them as one. If your material is subject to a specific regulatory regime, treat a shared password as what it is: a gate that anyone holding the password can pass through, and that you can close by changing the password or unpublishing the flipbook.