The <xforms:instance> element describes the result <response> XML structure that should be submitted with the answers to the form.
This structure contains entries for all the questions in the form with their default values and additional information that is used by ITP to track the order of the responses and state of elements in the form.
Processing applications should always copy this structure and replace the values that have been changed by the user. The additional elements with internal values as used by ITP should be copied verbatim. The application should be aware of and able to handle new values introduced in future versions of ITP.