[lxml-dev] Validation against an external DTD

Hello, I read through the documentation and I did not find a way to validate an XML-File against an external DTD with lxml. I searched the ML-archive and found several posts but I still do not know exactly, if this functionality is available or not. Right now I am using pyxml to do validation, but since the whole process will switch to xml schemes I am looking for a tool that can validate both (XSD,DTD). Is it possible to extend lxml to do this? I know that I can use a tool like "trang" to convert the DTDs but since there are DTDs that get added or removed from the process this means a lot of manual work. Kind regards, Michael