Torsten --

I'm not sure I understand the question correctly (e.g. are you
encoding a particular questionnaire, or a set of questionnaires, or a
system for any questionnaire?). But FWIW my first instinct is that
Peter's customization suggestion is along the right track. The twist
will be coming up with the right level of generalization.

* A new element for each question (as Peter implied, although he used
  the same ident= twice, I presume that's a typo)

* A new element for each type of question, e.g. <true-false>,
  <true-false-na>, <mult_choice>, <mult_choice_with_other>

* A single element <question> that lets you control the type of
  response with a responseType=. Current ODD processing doesn't make
  it easy (if even possible) to validate the response against the
  specified responseType=, but don't let that stop you :-)

Issues like that.