Single sourcing demands modular documentation. This document type allows to create and store these modules to be reused by transclusion. The lifetime of a module document is independent of the lifetimes of the documents that reference it. This is different from the Section doctype, where the lifetime of the referencing parent doctype is usually bound to that of the sections. To aggregate documents use the topic documentation type. Topics may then themselves, together with other document types, be assembled by Tour documents. | 
