ePublisher accepts ditamaps as input source documents. The ditamap identifies the structure and order of the XML files and the DTD. The DTD defines the classes for each element, such as topic/topic and task/task. ePublisher uses these classes to process the content. ePublisher also allows you to add individual XML files as source documents to a project. However, if you publish individual XML files without using a ditamap, links will not be generated in the output.