I am trying to query a MapServer layer via URL, but I am having trouble finding syntax examples. I want to use the indexquery mode and found this documentation http://gislars.github.io/mapserver_docs/cgi/controls.html as well as this http://mapserver.org/tutorial/example1-1.html. I am successful in returning the layer in map mode, but am not sure how to structure the indexquery string.
UPDATE: Upon further investigation it seems I need to use itemnquery mode. I have found some syntax that seems like it should work in this thread https://github.com/mapserver/mapserver/issues/4711, but I don't have access to the column names, and am not sure how to get them. Ultimately I'd like to query all records. Is there a general query for selecting all records, or is there a way to query a layer to return field names?