Standard use case for this is where users are presented with a GUI form with multiple input boxes, each targetting a different field and allowing "lucene syntax". The XML query template behind such a form would have a <UserQuery> tag for each form field, each defined with the appropriate choice of default field name.
Added Junit test for changing default field name, updated DTD for XML query syntax and regenerated HTML documentation.
git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@674975 13f79535-47bb-0310-9956-ffa450edef68