The concept of paths was extended to "guided tours" in NoteCards [Trigg,1988]. A guided tour is a system-controlled navigational tool that can be entered and exited at the user's will. Progress can be monitored using maps or overviews of the hypertext database. In NoteCards, a guided tour can be accessed through a graphical browser (which displays a portion of the hypertext network in terms of cards and links) by both authors and readers; the "stops" on the guided tour are sets of cards arranged on the screen according to a particular layout, also called the "tabletop". Thus, a guided tour is a graphical interface to a network or path of tabletop cards, connected by links. A tabletop is a snapshot of cards currently on display, including their positions, shapes, scrolled locations of their contents and any overlapping. The decision about what cards to include in the tabletop is left to the author. Tabletops, in addition to saving individual card layouts, can be used to make online presentations and hard-copy screen shots or transparencies for offline presentations. Editing tools are available for creating and managing both tabletops and guided tours.
A reader has necessary controls to start a guided tour, traverse a path of tabletops in sequence, jump arbitrarily to any tabletop, go back and forth between tabletops or reset the state of the guided tour. Facilities are also available to peek into tabletops in a path without actually "opening" them. Guided tours, I would add, are like "hypertext within hypertext". They help bridge the communication gap between hypertext authors and readers. They make the contents of a document intelligible to people who are not already familiar with it - things like a description of their contents, the rationale behind their contents, an explanation about the context of their use and a history of their construction. A demonstration can be carried out by the author, in absentia, using guided tours. Trigg refers to this advantage of remote pointing as "remote deictic reference".
Nielsen feels that even though a guided tour seems to limit the very purpose and potential of hypertext, it can be used to introduce the concept of hypertext to new readers and for small systems. Different levels of guided tours can be designed for different types of users [Nielsen, 1990b].