[Zope] howto keep doc-types via WebDAV?

Hi zopies! I use davfs to edit my documents on the zope-server. I edit them on my local filesystem, then copy them to the remote server. All docs are after this ceremony from the type: text/x-unknown-content-type. How can I achieve to keep the type, e.g. dtml-docs ? I tried different suffixes (bla.dtml etc.) - No effect. I couldn't find anything in the davfs docu. Thank you in advance, Florian