we had dcrs which were of iwov type but now we want to have dcr type xml. Is there any Interwoven defined path for this
There's no OOTB utility that will provide a simple means to do this. You'll have to revised the DCT and then change the PT and all of the pre-existing DCRs.It's probably best to do this as a phased-in approach where you create a new data-type for the "xml" style of DCT (e.g.: "iwov" -> article, "xml" -> new_article) and then train the users to use the new_article data type and over time work on transferring the content from article DCRs into new_article DCRs of the same name, set to create generated files of the same name in the same location - as you do this, you can delete the old DCRs.Otherwise you need to use something like XSLT or TeamSite::XMLnode (or various other things) to convert the old DCRs to the new format and hope your conversion works correctly and you don't accidently lose any original data.