Various attributes can be placed on the submission element to control the serialization of the submitted instance document:
<submission
action="http://www.example.org/formprocessor.php"
method="post" id="q0"
version="1.0"
indent="false"
encoding="ISO-8859-1"
omit-xml-declaration="true"
/>version: 1.0 or 1.1
indent: whether or not to pretty print the submission
encoding: Character encoding for the submission
omit-xml-declaration: whether or not to include an XML declaration with the submission
cdata-section-elements: list of elements whose contents are emitted as CDATA sections rather than using & escaping or numeric character references
Mostly these are copied from XSLT. However values are "true" and "false" rather than "yes" and "no".