Metadata filtering provides data filtering and an additional layer of security. With metadata filtering, an administrator can remove outline members from a user's view, providing access only to those members that are of interest to the user.
When a filter is used to apply MetaRead permission on a member:
Data for all ancestors of that member are hidden from the filter user’s view.
Data and metadata (member names) for all siblings of that member are hidden from the filter user’s view.