Advanced filter options "exclude"

when searching for items (projects, schedules, metrics, ...) i'm able to look for certain tags or flags.

i would love to see an option to "exclude" all items that do not contain a certain flag

examples from the past where i could have used this option

- show any calculated metrics that do not contain "test" => exclude tag "test"

- show all calculated metrics that have no flags => exclude all tags

- show only projects from other users => exclude "mine"

- show projects that are approved but not shared with certain group => include "approved", exclude "certain group"

i think there are a lot more examples where an exclude option could be useful