A DTD-compliant XML document editor is disclosed. The XML document editor generates hints for required elements and required element slots automatically in the process of document creation and edition so as to guide the user to produce a valid document, while syntactic violations are avoided at the same time. The editor also suggests optional elements that may be added into the document to be edited. The user requires no knowledge about XML and DTD to edit DTD-compliant XML documents. The editing process is user-interface-neutral, being able to support user interfaces based on tree views, presentation views and forms. By combining the DTD-compliant editing process with the simplicity of forms, a simple XML document editor with forms as its user interface is developed.