1. A computer-implemented process for creating an adaptive document, comprising using a computer to perform the following process actions: inputting manifold representations of alternate document content that are modified versions of a same document content; creating a document tree by associating each representation of alternate document content with a tree data structure, wherein OR nodes are used to organize said manifold representations of alternate document content in said tree data structure; creating a new representation of alternate document content in the document tree by the following process actions: inputting selected document content and said document tree; looking for a document sub-tree that can exactly generate a selected region of the selected document content; when an exact sub-tree is not found, creating a new sub-tree corresponding to the region of selected document content; and creating a new representation of alternate document content by modifying the document tree so that the created sub-tree corresponding to the region of selected document content becomes a child of a new OR node; when an exact sub-tree corresponding to the selected document content is found, creating a new representation of alternate document content by modifying the document tree so that the found exact sub-tree corresponding to the region of selected document content becomes a child of a new OR node; and automatically formatting said manifold representations of document content to fit a viewing situation using said modified document tree, constraints and user preferences.