Filter Members by Security

So we have the GetBaseMembers method (or the GetChildren, or the GetDescendant or event the GetMember) that would return instances of the Member class.

What is not clear (at least to me) is how I could filter returned members based on security.

I could set Nobody in all the member Security's fields of a specific member, but it keeps on being returned by (for instance) the GetBaseMembers.

I'm wondering how I could get only visible members, applying a filter that won't return them from the call.

Also, it would be nice to know, given a member, if it can be seen, read or written.

Two ways to get the same result, for different scopes.

Thanks

FabioG