You can install or update DTDs, configure the catalog, and configure DITA specialization for use with XMetaL.
Installing new or updated DTDs on the server If you want to add a new DTD or modify an existing DTD, you need to copy all the relevant files to the server on which SDL LiveContent Architect is installed. The next time that a user connects to the repository, the updated files are synchronized to the client application.
Configuring the OASIS catalog Reference to the DTD is required to validate XML files. The catalog file identifies the DTD and where it can be found by any component of the system.