Apparatus and methods of revealing the hierarchical structure of a
document having content of a characteristic type of content are
described. The hierarchical structure may be expressed, independently of
document content type, as a tree structure of one or more nodes. A
semantic representation for interpreting the tree structure may also be
provided. Document description files are used to encapsulate structural
and meta information associated with a document stored on a
computer-readable medium. Document description files are external to
native application files and have a set of required fields. Document
description files point to the referenced document data using Uniform
Resource Locators (URLs) and serve as virtual documents. In addition to
the required fields, applications can choose to encode additional
structural information in the document description files.