I'd like an api / obs_search_url param for not equal to a term_value_id (e.g. term_value_id is NULL or != the term_value_id) - something like
http://www.inaturalist.org/observations?place_id=any&subview=grid&term_id=9&term_value_id_not=11&order_by=votes
which would return all observations except those with term_value_id = 11