this is probably documented in the source code but I could not find references at the forum search tool nor google search.
Scenario: we implementing a change in Wifi configuration on all CPEs. Each CPE with the change gets tagged, so I wanted to get the list of devices which still have to be configured.
As usual it was by accident, while filtering devices by two tags at the same time, I took notice of the AND operator at the url.
So I replaced it by:
NOT Q(“Tag”, “falta”)
which brought the list of devices without the tag falta.
It also works with other kind of filters. In our case we also had “SW Version” (software version) which is added in the config page.