...has the default value of yes, as noted at http://docs.basex.org/wiki/Serialization, the XQuery Serialization does not appear to recommend/enforce a default (http://www.w3.org/TR/xslt-xquery-serialization-30/#XML_OMIT-XML-DECLARATION), but the XForms spec does (http://www.w3.org/TR/xforms11/#submit) and the recommendation in XForms spec is the default value of false (=no), which is different from the default value of yes(=true) used by BaseX.
While it (the way things are) is not a major (or minor) headache (for me), if it is a minor change and can be factored in in some future release, that would be useful (it would mean I have to set one less query param if I want the default behaviour of XForms).
Thanks.