The method enables a new DTD to be dynamically created during runtime from a preexisting DTD. A next document is processed and validated according to the new DTD. An interface is provided that enables plug-in providers to provide fragments of DTD information for at least one new element to be added and the name of the element that is to be added to an existing parameter entity. All of the fragments from each plug-in provider are concatenated together and combined with the static header information of the preexisting DTD to form the new DTD.