I tried do following in index_html:

<dtml-var obj>

But this echoes only plain text ('path.to.object.file') and not the object's content. I need to find some way how to convert this string to object, so Zope (or Python) can understand it as an object and display its content. Is there some way? You could try:

<dtml-var "REQUEST.resolve_url(obj)"> Regards, Josef