The top pane in Figure 1 shows the IRIS InSight document library, in which books for different types of users or applications are arranged on named bookshelves. A user can directly view an online book by double-clicking its icon or title. Alternatively, the user can search for information in one or more selected books by single-clicking them and then typing the search terms or phrases into the search field (in the middle of the screen shot in Figure 1). Boolean and proximity operators can be used to refine a search. The sections of books in which the search terms can be found are displayed in a "hit list" the lower pane of Figure 1.
The display of a selected book or book section appears as in Figure 2. The display is organized as a "structure view" in the top pane and a "content view" below it. In Figure 2, the structure view in the top pane is the book's table of contents, presented as a dynamic outline for progressive display of details [3, 12], but other structure views like lists of tables, figures, or code examples are also available. Searches can be restricted to a particular kind of content element for more precision; for example, a user can search only in titles, figure captions, or code examples. The content and structure views are synchronized so that a user can quickly navigate to any part of the book by double-clicking on an item in a structure view.
The user's current position in the book is indicated by highlighting a title in the structure view. Numbers in front of each title indicate the number of matches to the current search expression (indicated in the within-book search field at the bottom of the window in Figure 2). This structured search feedback technique, first used by SuperBook [11], has been shown to enhance search and navigation in online publications [2].
In the content view in the bottom pane of Figure 2, the text of the book appears in a scrolling window. This display is NOT page-based; the window can be arbitrarily resized, and the text is wrapped and reformatted as needed. Selectable "See" and "See also" cross references to another section or book (hypertext links) are marked on the screen by presenting them in a distinctive color. Links within a book instantly scroll the content and structure views within the same window, while links to another book open a new window. Glossary terms, marked by underlining, open a window containing their definitions when they are selected.
IRIS InSight books can contain in-line or link to graphics, audio, video, animation, and other digital media elements for which Silicon Graphics computers are exceptionally well-suited. A sample screen display appears in-line in Figure 2, but a reader can instead specify that all non-text elements be represented by an icon at the right margin and presented in another window only if selected. Readers can select from a variety of "style sheets" or presentation specifications that change fonts, type size, or other presentation characteristics for a particular book or for the entire library.
The paper clip icon in the right margin indicates a "bookmark", which users can create to mark and return to important locations. Another navigation feature shown in Figure 2 in the lower right corner of the window is a Go Back button, which retraces the reader's steps to re-display previously displayed books. Readers can also navigate by selecting hypertext links from entries in an alphabetic "back-of-the-book" index.