It could be useful to be able to have "pseudo structures" like:
and do something like a "foreach()":
$doc->iterate('mylist', 'listitem', array('line 1', 'line 2'));
that results in
* line 1
* line 2
Another (more or less related) extension could be like "print series": the document gets loaded, but fields gets replaced by arrays, resulting in a multi-page document.