A UI policy applies declarative field behavior when its conditions match. It can make a field mandatory, read only, or visible on the relevant form. Use it for straightforward presentation behavior before reaching for a client script. Test both the matching state and the state after the condition stops matching.
Reverse behavior matters. A field made mandatory for one state may need to return to optional when the record leaves that state. Form behavior is not a security boundary, and a browser-only rule does not automatically protect an API or import. Use appropriate server validation and access controls for requirements that apply across access routes. The course asks you to choose the right mechanism and reason about the boundary rather than claiming that a form-only rule secures all writes.