I have used this module to parse the SVG 1.1 DTD (www.w3.org/Graphics/SVG/1.1/DTD/svg11... which is extremely complex. Version 0.08 of XML::DTD did not parse it correctly, and since I knew hardly anything about DTDs I issued a quite vague bug report about it. The author was extremely responsive and despite my minimal help he fixed the problem within a day.
The documentation is quite sparse and although you can guess a lot of things it should be expanded considerably. However, again the author was fast and very helpful with answering my questions. Under normal circumstances, I would remove on star for the documentation, but the superb responsiveness of the author earns back the fifth star.