Inclusive and Exclusive would be nice too. Where the tags are assumed to start with + and are inclusive. But you could start tags with - which would make them exclusive and not get included in results. It would make it possible to filter by tag XXX and use exclusive (-) mode get all results but XXX. Filter by XXX in inclusive (+) mode and only get XXX. If no mode (- or +) is put in front it is assumed inclusive. Having AND with OR would be icing on the cake and allow setting complex fi