This is a generalized request based on SAT-26060.

As a user I'd like to search for fields which are null. For example, a host without any check ins will not show up in last_checkin > "6 days ago" nor last_checkin < "6 days ago". It is possible to use null? last_checkin but autocomplete doesn't suggest this nor is it documented (https://docs.redhat.com/en/documentation/red_hat_satellite/6.17/html-single/administering_red_hat_satellite/index#Searching_and_Bookmarking_admin).