. Navigational buttons serve as
'railings' and 'roadsigns' to guide the user through the session and to provide visual clues as
to what is behind the links. The home and arrow buttons facilitate navigation through the sections and subsections within this integrating document.
Top section is the section located at the highest level of this integrating hierarchical document.
One section up displays a section located above the current section inthis integrating hierarchical document.
One section down displays a section located below the current section in this integrating hierarchical document.
Previous section displays the next section in the current level of this integrating hierarchical document.
Next section displays the previous section in the current level of this integrating hierarchical document.
Other available links include:
Notes, references and glossary entries are (usually short) excursions outside the main hierarchical data structure.
Commentaries are author-signed extensions - to ecourage expression of multiple views and comments.
Linked topics is a jump to a list of somewhat related documents.
or 
Domain outline displays the contents as an outline. Users familiar with the domain prefer the direct access through the outline.
External domain outline displays the contents as an outline.
External document, outside this integrating hierarchical document.
Navigation help - access to this document.
Once the user leaves the domain of this document, the local navigation rules of the new domain apply.
These are experimental implementations of hypertext concepts and will ceratainly evolve with time.