seam is using XML scheams - XSDs - instead of DTD from early version of 1.2.x.
XSDs are located in related built jboss-seam jars.
For instance for PDF module XSDs you should looking at jboss-seam-pdf.jar or in sources in org.jboss.seam.pdf package.
I'm VERY noob with XSDs and didn't get it to work. How the
importwould look like?