I think it would be great to have a link to https://musicbrainz.org/doc/Development/XML_Web_Service/Version_2/Search here because it helps in understanding the search fields (what they mean and special cases like how to search for unset/unknown values) and not everyone knows what lucene is, how it works and/or what a lucene query looks like (and I hope we don't want to give an introduction to that :) )