A DITA authoring DTD generator for creating DTDs that are not valid specialization, but can be used for authoring purposes. See DITA Architectural Specification for limits of specialization, in particular chapter “Customized subset document types for authoring” for description of specialization possibilities. For valid specializations, see DITA Specialization Generator.
Note: There is a new version of the generator at DITA DTD Generator. It does not enable all the possibilities offered here, but is more robust and support DITA 1.2.