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Claims  |
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What is claimed is:
1. A computer controlled display system having a display, processor and a
cursor control device, said computer controlled display system for
controlling the display of a list of linked documents comprising:
document list generation circuitry coupled to access a collection of linked
documents, wherein a plurality of said collection of linked documents
reside on a common server, said documents residing on said common server
having relative links to other documents residing on said common server,
said document list circuitry for generating and obtaining an ordered list
of linked documents residing on said common server using said relative
links;
a storage device coupled to said document list generation circuitry, said
storage device for storing said ordered list of linked documents;
page object generation circuitry coupled to said storage device, said page
object generation circuitry for generating page objects for each document
in said list of linked documents, each of said page objects comprising a
content portion and a page control portion;
book generation circuitry coupled to said page object generation circuitry,
said book generation circuitry for generating a representation of said
ordered list of linked documents as a book for displaying on said display
based on the order of said list of linked documents, said book on said
display comprising:
a first area for displaying a first page object as a first left page of a
book displayed on said display, said first left page having active
contents when displayed;
a second area for displaying a second page object as a second right page of
said book displayed on said display, said second right page having active
contents when displayed; and
a control area for displaying control buttons, said control buttons for
enabling a user to generate input to said book generation circuitry for
generating subsequent representations of said list of linked documents.
2. The computer controlled display system as recited in claim 1 wherein
each of said first area and said second area is further comprised of a
scale control area for scaling the display of the content of a page
object.
3. The computer controlled display system as recited in claim 1 wherein
each of said first area and said second area is further comprised of a
vertical scrolling area for enabling vertical scrolling of the display of
the content of a page object and a horizontal scrolling area for enabling
horizontal scrolling of the display of the content of a page object.
4. The computer controlled display system as recited in claim 3 wherein
said book on said display further comprises page edge overlap areas for
indicating a relative page order of pages displayed in said first area and
said second area.
5. The computer controlled display system as recited in claim 4 wherein
said book generation circuitry further comprises page turning circuitry
for causing new page objects to be displayed in said book responsive to a
user interaction with said cursor control device in said first area, said
second area or said page edge overlap areas.
6. The computer controlled display system as recited in claim 5 wherein
said control area includes a first scan button for causing pages to be
turned in a first direction and a second scan button for causing pages to
be turned in a second direction.
7. The computer controlled display system as recited in claim 1 wherein
said control area includes a mark button for marking a page object
currently being displayed and causing a corresponding bookmark to be
displayed.
8. The computer controlled display system as recited in claim 1 further
comprising means for opening said book to the page displayed when the book
was closed.
9. The computer controlled display system as recited in claim 1 wherein
said book in said display further comprises re-sizing areas for changing
the size of said book.
10. The computer controlled display system as recited in claim 1 wherein
said book generation circuitry further comprises highlighting circuitry
for causing links within said list of linked documents to be displayed in
a first visually distinct manner and links outside of said list of linked
documents to be displayed in a second visually distinct manner.
11. On a computer controlled display system having a display and a cursor
control device, a method for presenting lists of linked documents for
viewing which are part of a collection of linked documents, wherein a
plurality of said collection of linked documents reside on a common
server, said documents residing on said common server having relative
links to other documents residing on said common server, said method
comprising the steps of:
a) obtaining an ordered list of linked documents and the content of said
linked documents residing on said common server using said relative links;
b) generating page objects for each linked document, said page objects
containing the content of an associated linked document and page control
information;
c) organizing said generated page objects in a computer displayable
representation of a book according to the ordered list, wherein each page
object corresponds to a document in said ordered list of linked documents,
each of said page objects being active when displayed, said representation
of a book further containing a plurality of control areas for turning
pages of said book, each of said plurality of control areas causing pages
to turn in a predetermined action;
d) a user opening said book;
e) rendering and displaying said active page objects of said book on said
display; and
f) said user viewing and traversing said book by invoking a page turning
operation in said plurality of control areas or by selecting links to
other documents in said ordered list of linked documents until finished
with viewing said book.
12. The method as recited in claim 11 comprising the steps of:
i) said user re-opening said book; and
j) displaying said book at said marked last open page.
13. The method as recited in claim 11 said step of said user traversing
said book by invoking page turning operation in said plurality of control
areas until finished with viewing said book is comprised of the steps of:
said user operating a cursor control device to position a cursor into a
desired control area;
said user invoking a desired turning operation using a predetermined
interaction; and
turning pages of said book in the direction associated with said desired
control area and in the manner associated with said desired page turning
operation.
14. The method as recited in claim 13 wherein said predetermined
interaction is a single click on said cursor control device and said
desired page turning operation is a single page turn.
15. The method as recited in claim 13 wherein said predetermined
interaction is a click and hold on said cursor control device and said
desired page turning operation is a page ruffle.
16. The method as recited in claim 11 wherein concurrent with said step of
said user traversing said book by invoking page turning operation in said
plurality of control areas until finished with viewing said book,
performing the steps of:
said user indicating a page to be marked;
displaying page marks on said marked page; and
updating said book representation to include the marked pages so that when
the book is re-opened the page marks are displayed.
17. The computer controlled display system as recited in claim 1 wherein
said document list generation circuitry is further comprised of circuitry
for creating an ordered list of linked documents based on said relative
links.
18. The computer controlled display system as recited in claim 17 wherein
said book generation circuitry is further comprised of circuitry for
ordering pages in said book based on said ordered list of linked
documents.
19. The method as recited in claim 11, wherein said step of obtaining an
ordered list of linked documents and the content of said linked documents
is further comprised of the steps of:
a1) selecting a first document at said common server and ordering as a
first document in said list of linked documents;
a2) finding relative links in said first document and retrieving the linked
documents;
a3) finding relative links in subsequently retrieved linked documents and
retrieving the linked documents until all relative links have been found
and corresponding documents retrieved; and
a4) ordering said linked documents in the order that they are retrieved.
20. An article of manufacture comprising:
a computer usable medium having computer readable program code means
embodied therein for enabling a computer to present viewable lists of
linked documents, the computer readable program codes means in said
article of manufacture comprising:
computer readable program code for causing a computer to access a
collection of linked documents, said collection of linked documents having
a plurality of documents at a common server, said documents at said common
server linked by relative links;
computer readable program code for causing said computer to generate an
ordered list of linked documents residing on said common server using said
relative links;
computer readable program code instructions for causing said computer to
generate page objects for each document in said list of linked documents,
each of said page objects comprising a content portion and a page control
portion, said content portion including links to other documents in said
ordered list of linked documents;
computer readable program code for causing said computer to generate a
representation of said list of linked documents as a book for displaying
on a display coupled to said computer, said representation based on the
order of said list of linked documents said book on said display
comprising:
a first area for displaying a first page object as a first left page of a
book displayed on said display, said first left page having active
contents when displayed;
a second area for displaying a second page object as a second right page of
said book displayed on said display said second right page having active
contents when displayed; and
a control area for displaying control buttons, said control buttons for
enabling a user to generate input to said book generation circuitry for
generating subsequent representations of said list of linked documents;
and
computer readable program code for enabling a user to traverse through said
list of linked documents as if they were turning pages in a book by
selecting links in said content portion of a page object.
21. An article of manufacture comprising:
a computer usable medium having computer readable program code means
embodied therein for enabling a computer to present viewable lists of
linked documents, the computer readable program code means in said article
of manufacture comprising:
computer readable program code for causing a computer to access a
collection of linked documents to create a list of linked documents;
computer readable program code instructions for causing said computer to
generate page objects for each document in said list of linked documents,
each of said page objects comprising a content portion and a page control
portion, said content portion capable of including links to other
documents in said list of linked documents;
computer readable program code for creating a representation of said list
of documents using said page objects created for each document in said
list of documents, said representation displaying a plurality of page
objects simultaneously, and wherein each page object is active when
displayed.
22. The article of manufacture as recited in claim 21 wherein said computer
readable program code means is further comprised of:
computer readable program code for circuitry for ordering said list of
documents; and
said computer readable program code for creating a representation of said
list of documents, creates said representation according to said order of
said list of documents.
23. The article of manufacture as recited in claim 22 wherein said computer
readable program code for creating a representation of said list of
documents, creates said representation using a book metaphor. |
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Claims |
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Description |
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FIELD OF THE INVENTION
The present invention is related to the field of computer user interfaces,
in particular a user interface for viewing related documents.
BACKGROUND OF THE INVENTION
The growth of the Internet, and in particular, the facet of the Internet
known as the World-Wide-Web (referred to simply as the Web) has been very
explosive. The Web provides a means for making multi-media styled
documents over the Internet. These documents are termed Web pages
(hereinafter pages). Pages may refer to and provide access to other pages
on the Web. Each page has associated with it an identifier termed a
Uniform Resource Locator (URL). A page is accessed by specifying it's URL.
The contents of a page is specified in a document formatting language
known as the Hyper-Text Mark-Up Language (HTML). A reference to another
page on the Web is termed a link. Links may be specified in either
absolute or relative terms. A link specified in absolute terms refers to
it's entire URL. A link specified in relative terms assumes a certain
portion of the URL is the same as the existing page. The specification is
thus relative to the URL of the page on which it is defined.
To access and view a document on the Web, a Web browser is needed. A Web
browser provides search, traversal and viewing functions needed to access
documents on the Web. Various Web browsers exist for the Web, e.g.
NetScape from NetScape, Inc. of Mountain View, Calif. or Mariner from
Network Computing Devices Corporation of Mountain View, Calif. Traversing
through documents contained on the Web is similar to following a path
through a network. Since each page may contain links to many other pages,
traversing through the pages is a simple matter of following the links.
Most Web browsers provide controls for going backwards and forwards in the
list of links. They also maintain a history list of the links to enable
jumping directly to a specific previously viewed page.
Most publicly available Web browsers only display one page at a time. The
user interface for Web Browsers typically correspond to the capabilities
of the computer system on which it resides. A full featured Web browser
may provide rendering means for viewing audio, video and graphical
portions of documents as well as a graphical user interface for
controlling access to documents. The graphical user interface is typically
one which provides for vertical and horizontal scrolling via scroll bars
and point and click manipulation of a cursor control device to invoke
browser operations (e.g. to traverse links). Color, underlining or reverse
video are techniques used to indicate the existence of a link on a page.
A more robust Web Browser is described in "Deckscape: An Experimental Web
Browser", Marc H. Brown and Robert A. Shillner, DEC Systems Research
Center Report 135a, Mar. 1, 1995. The DeckScape web browser utilizes the
metaphor of a deck as a collection of Web pages. Only one Web page on a
deck is visible at one time, although multiple decks may be visible.
DeckScape is also multi-threaded so that each deck may be "active", e.g.
downloading pages, at the same time. A deck may be created based on a
traversal through the Web or as the result of an operation such as "expand
all the links on this page."
The present invention uses a book metaphor to enable a user to browse
through a list of web pages. The use of a book metaphor on computer based
systems is known in the art. Such a book metaphor has been used as an aid
for organizing related files and/or applications. Examples include the
TabWorks product available from X-Soft, a division of the Xerox
Corporation of Palo Alto, Calif., and the SGI DemoBook available on
graphical workstations from Silicon Graphics, Inc. of Mountain View,
Calif. The metaphor of a notebook is also used in pen based systems (e.g.
the PenPoint Operating systems from the Go Corporation) and personal
digital assistants (e.g. the Magic Link product from Sony Corporation).
SUMMARY OF THE INVENTION
A display system for displaying lists of linked documents is disclosed. The
present invention is implemented for displaying lists of pages downloaded
from the World Wide Web. A list of pages will typically be related in some
way. For example, the list of pages may include all the pages defined as
relative links on a home page. A home page is typically an entry point for
gaining information on a particular person, product, company ,etc., and
the relative links are relative to the Uniform Resource Locator (URL)
address of the home page.
The list of pages is displayed in a book metaphor, termed a WebBook, on a
computer controlled display system. The book metaphor is desirable since
it inherently conveys the notion of the pages being related. When
displayed, two active pages are displayed at one time. To enable the book
metaphor, each page in the list is converted into a page object. Each page
object will represent either an left or right page. Page objects
representing a left page will have an axis of rotation along a right edge
(as viewed by a user) while page representing a right page will have an
axis of rotation along a left edge (as viewed by a user). When positioned
on the WebBook, the position of the axis of rotation is generally the same
as the spine of the WebBook.
The turning of pages in the present invention is animated. The animation
sequence for turning or ruffling pages is generally the same. Ruffling can
be thought of as multiple concurrent page turns. Generally, the sequence
of steps is to rotate the page to be turned about the axis of rotation,
rotate the page on the other side of the page to be turned about the axis
of rotation, at a point orthogonal to the viewer, turn off the page to be
turned and turn on the page on the other side, turn off the page being
covered, and turn on the new page being revealed by the page turn.
Various user interface controls are provided for traversing the pages of
the book, creating book marks, scanning pages, scaling the contents of a
page, scrolling through pages, etc.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a computer controlled display system as may be
utilized in the currently preferred embodiment of the present invention.
FIG. 2 is flowchart illustrating the basic steps for creating and operating
a WebBook in the currently preferred embodiment of the present invention.
FIG. 3 is an illustration of an open WebBook in the currently preferred
embodiment of the present invention.
FIG. 4 is an illustration of a first page of a WebBook without a cover.
FIG. 5 is an illustration of a WebBook having a cover.
FIG. 6 is a block diagram of a WebBook data structure.
FIGS. 7 and 8 are illustrations of a spatial perspective of left and right
page objects.
FIG. 9 is a block diagram of a Page Object data structure.
FIGS. 10 and 11 are a series of illustrations showing a page turn of the
WebBook.
FIG. 12 is an illustration of ruffling through the pages of a WebBook.
FIG. 13 is an illustration of a pop-up window for controlling temporal
parameters for animating page turns.
FIG. 14 is an illustration of the scaling of page contents on a page of the
WebBook illustrated in FIG. 3.
FIG. 15 is an illustration of a web browsing system of which the currently
preferred embodiment of the present invention may be used as a component.
DETAILED DESCRIPTION OF THE INVENTION
A portion of the disclosure of this patent document contains material which
is subject to copyright protection. The copyright owner has no objection
to the facsimile reproduction by anyone of the patent document or the
patent disclosure, as it appears in the Patent and Trademark Office patent
file or records, but otherwise reserves all copyright rights whatsoever.
A display system for displaying lists of linked documents is disclosed. An
example of linked documents are hyper-text documents in a hyper-text
system, e.g. the HyperCard system from Apple Computers of Cupertino Calif.
The present invention provides a higher level of abstraction for systems
which traverse through linked documents. This abstraction provides for
organizing and providing access to documents using a metaphor which
inherently indicates a relationship between the documents.
The currently preferred embodiment of the present invention is implemented
for use on lists of linked documents obtained from the portion of the
Internet known as the World Wide Web (hereinafter the Web). However, it
should be noted that the present invention is not limited to use on the
Web and may be utilized in any system which provides access to linked
documents. The following terms defined herein are familiar to users of the
Web and take on these familiar meanings:
World-Wide Web or Web: The portion of the Internet that is used to store
and access linked multi-media documents.
Page: A document accessible on the Web. A Page may have multi-media content
as well as relative and absolute links to other pages.
Home Page: A page functioning as an entry point to a set of related pages
on the Web. A home page will typically have a plurality of relative links
to related pages.
Hyper-Text Mark-Up Language (HTML): The formatting language for specifying
the contents of a page.
Uniform Resource Locator (URL): The address or identifier for a page on the
Web.
Server: An addressable storage device residing on the Internet which stores
Web Pages.
Link: An indicator on a Web page which refers to another Web page and which
can typically be retrieved in a point and click fashion. The Link will
specify the URL of the other Web page.
Relative Link: A Link with a URL that is specified relative to the Web page
on which the link exists. Relative links are used for groupings of related
pages that typically reside on the same server so that these groups of
pages can be easily moved without having to modify the link specifications
in the group of related pages.
Absolute Link: A URL that provides a full or actual URL address for a page.
Web Browser or Browser: A tool which enables a user to traverse through and
view documents residing on the Web. Other rendering means associated with
the Browser will permit listening to audio portions of a document or
viewing video or image portions of a document.
The present invention is implemented for use for viewing lists of linked
documents. This capability of viewing lists is a component of a system for
interacting with pages downloaded from the Web. This system is described
in greater detail below. A list of linked documents can be created in
various ways. One such way is to follow the relative links on a "home
page". Another way would be to create the list manually by traversal
through pages on the Web.
The currently preferred embodiment of the present invention presents the
list of pages to a user in a book metaphor hereinafter referred to as a
WebBook. The book metaphor is useful since it conveys a relationship
between the different pages. Each page in the WebBook represents a page in
the list. When the WebBook is open, two pages are visible. Each page has
its own set of page controls. The WebBook is implemented for display on a
Computer Controlled Display System which is described below.
Conceptually, the WebBook provides a new way of interacting with and
organizing Web pages. Heretofore, only individual pages are transmitted on
the Web. Any relationship between the pages received is determined by the
person accessing the pages. Using the notion of the WebBook, pages could
be organized so that lists of pages could be easily transmitted. So for
example, a company wanting to provide information about its products could
take advantage of relative links and organize a home page to have relative
links to all its products descriptions. A user could subsequently access
this home page download the homepage and the pages at its relative links
and create a WebBook about that company's products.
Overview of a Computer Controlled Display System in the Currently Preferred
Embodiment of the Present Invention
The computer based system on which the currently preferred embodiment of
the present invention may be implemented is described with reference to
FIG. 1. The computer based system and associated operating instructions
(e.g. software) embody circuitry used to implement the present invention.
Referring to FIG. 1, the computer based system is comprised of a plurality
of components coupled via a bus 101. The bus 101 may consist of a
plurality of parallel buses (e.g. address, data and status buses) as well
as a hierarchy of buses (e.g. a processor bus, a local bus and an I/O
bus). In any event, the computer system is further comprised of a
processor 102 for executing instructions provided via bus 101 from
Internal memory 103 (note that the Internal memory 103 is typically a
combination of Random Access and Read Only Memories). The processor 102
will be used to perform various operations in support of obtaining Web
pages and converting into a suitable format for the WebBook. Instructions
for performing such operations are retrieved from Internal memory 103.
Such operations that would be performed by the processor 102 would include
the processing steps described in FIG. 2. The processor 102 and Internal
memory 103 may be discrete components or a single integrated device such
as an Application Specification Integrated Circuit (ASIC) chip.
Also coupled to the bus 101 are a keyboard 104 for entering alphanumeric
input, external storage 105 for storing data, a cursor control device 106
for manipulating a cursor, a display 107 for displaying visual output
(e.g. the WebBook) and a network connection 108. The keyboard 104 would
typically be a standard QWERTY keyboard but may also be telephone like
keypad. The external storage 105 may be fixed or removable magnetic or
optical disk drive. The cursor control device 106, e.g. a mouse or
trackball, will typically have a button or switch associated with it to
which the performance of certain functions can be programmed. The network
connection 108 provides means for attaching to a network, e.g. a Local
Area Network (LAN) card or modem card with appropriate software. The
network ultimately attached to is the Internet, but it may be through
intermediary networks or On-Line services such as America On-Line, Prodigy
TM or CompuServ TM.
The present invention is implemented on a computer controlled display
system having a Graphical User Interface (GUI). Such a GUI will also
support operations such as "point and click". A "point and click"
operation is one where a cursor on a display screen is positioned over a
desired portion of the display, such as an icon, using a cursor control
device such as a mouse or trackball. Once the cursor is appropriately
positioned, a button/switch associated with the cursor control device is
quickly depressed and released. This creates an electrical signal which
causes a predetermined and context dependent operation to occur. Other
operations may require a "drag" where the button/switch is depressed to
"pick-up" and move an object and released to "drop" the object.
The currently preferred embodiment of the present invention has been
implemented on a Silicon Graphics workstation with graphics facilities as
described in SGI Graphics Library Programming Guide, Silicon Graphics,
Inc. of Mountain View, Calif. The Silicon Graphics workstation provides
for manipulating graphical objects in a three dimensional space. However,
it would have been apparent to one of skill in the art to implement the
present invention on other suitable computer systems providing graphical
functionality which manipulate graphical objects in a two dimensional
space. Such implementations would not depart from the spirit and scope of
the present invention.
Overview
FIG. 2 illustrates the steps for generating and using the WebBook of the
present invention. Referring to FIG. 2, the first step is to generate or
otherwise obtain a list of Web Pages, step 201. This can be accomplished
in various ways. One way is to analyze a page, such as a home page, and
follow and download all the relative links on the home page. This is
repeated for each subsequent page. Following relative links is useful
since these pages will typically be closely related. Each page on a chain
of relative links would then be included in the set of pages. Variations
on this would limit the number of relative links traversed. This list of
pages will be in the order that they would appear in the book.
Next, page objects for each web page are generated, step 202. A page object
is the internal representation of a web page for use in the book metaphor.
Page objects and their contents are described in greater detail below.
Next, the WebBook is generated from the page objects, step 203. The
WebBook has a basic structure which lists the pages and provides various
controls. When a user opens the WebBook it is rendered by the computer
controlled display system and displayed on a display, step 204. The first
time the book is opened, the cover will be displayed, or alternatively a
first page (depending on whether the book has a cover). Subsequent
instances of opening the book will cause it to be opened at the point
where it was last closed. As will be described in detail below, only those
pages corresponding to a particular page in a book are visible. Other page
objects are marked as not displayed.
The user then traverses the WebBook using page turning operations and
marking interesting pages until they are done viewing or using the
WebBook, step 205. The page turning operations are animated so as to give
the user a sense of an actual page turning. When they are done, the page
in the WebBook last open is marked in the WebBook, step 206 and WebBook is
closed, step 207. Optionally, the WebBook may be stowed, step 208. Stowing
the WebBook is equivalent of putting a book on a bookshelf.
WebBooks themselves may be organized as collections and stored as icons on
a bookshelf. This would permit the storing of multiple WebBooks each
having their own related subject. WebBooks may also be transferred and
used by other users. Finally, pages may be added to a WebBook. This would
require creation of a page object(s) for the added page(s) and
regeneration of the WebBook.
FIG. 3 is an illustration of a WebBook as displayed on a display. Referring
to FIG. 3, the WebBook 301 is comprised of a first page 302 and a second
page 303, each having an identical structure. The first page 302 is an
instance of a left page and the second page 303 is an instance of a right
page. Vertical scroll bars 304 and 305 provide for vertical scrolling on
their respective pages. Horizontal scroll bars 306 and 307 provide for
horizontal scrolling on their respective pages. Superimposed within the
horizontal scroll bars are page references 322 and 323 which indicate the
page number in the book for each page. Scaling bars 308 and 309 enable
font scaling on the respective pages. Each of the pages also has a title
bar 310 and 311 which is used to indicate the title of the respective
page. The content and layout of the page is determined by the HTML macros
defining the page.
Book control buttons are presented at the bottom edge of the WebBook 301. A
close button 312 provides for closing the book. A back button 313 provides
for looking at a prior page. A history button 314 provides for reviewing
the history of pages looked at. A mark button 315 provides for creating a
bookmark for a page being viewed. Such a bookmark 320 is illustrated in
FIG. 3 indicating that page 14 has been marked. A help button 316 provides
for invoking various help functions for the WebBook 301. The help
functions are in the form of text describing how to perform particular
functions in the WebBook. The options button 317 provides for specifying
various operational parameters in the WebBook. An example is specifying
the timing for flipping pages in the WebBook. The button 318 labeled "Scan
<" provides for automatic scanning of pages to the lower numbered
pages. The button 319 labeled "Scan >" provides for automatic scanning
of pages to the higher numbered pages. Re-sizing boxes 321 may be used to
re-size the WebBook 301 using a point and drag function.
Finally, book edge areas 322 and 323 are used to provide a visual
indication of relative positioning within the book, e.g. the number of
pages on that "side" of the book. The book edge areas 322 and 323 will
change in size as the pages are traversed. Also, the book edge areas may
be used as a means for directly accessing pages in the book (e.g.
mimicking the activity of thumbing through the book in groups of pages).
This is accomplished by a point and click operation pointing to the edge.
It should also be noted that color or some other highlighting technique may
be used with respect to the page contents to indicate links to other
pages. Note that these links and the highlighting technique are defined
within the HTML specification for the page contents. A particular color
may denote a link to a page within the WebBook, and another color used to
indicate a link to a page external to the WebBook. Generally, a point and
click operation on the highlighted portion will cause the linked-to page
to be accessed and displayed.
A WebBook may be displayed without a cover (FIG. 4), or with a cover (FIG.
5). Referring to FIG. 4, when displayed without a cover, the first thing
that a user will see is the first page in the created list of pages.
Further, when displayed without a cover, the first page will be a right
page in the WebBook. Referring to FIG. 5, when displayed with a cover, the
contents of the WebBook is hidden. Display of a cover may be useful for
security purposes, wherein a password or other security mechanism may be
required before the book may be opened. Further, when disp | | |
