Abstract:
The reading and writing system enhances free-form ink annotating and note taking by creating links between passages in response to free-form ink. The reading and writing system generates links between free-form ink anchors and also generates links between documents in different windows when a free-form ink stroke extends across window boundaries. The reading and writing system also removes a link when the free-form ink stroke representing the link is erased. The reading and writing system will display the ink anchors in a display showing all related linked anchors with their surrounding context when a corresponding link is selected.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This application is directed to a paper-like hypertext system that supports reading and browsing. In particular, the invention is directed to the creation of ad-hoc links between user-specified passages in documents using free-form ink annotations. 
     2. Description of Related Art 
     People use annotations and notes to organize information. Although annotations and notes serve the same purpose, there are many tradeoffs between marking on the document and marking in a separate place. Notes are concise to review, but take more effort to create. Notes have more context from the reader&#39;s ideas but less context from the document and short annotations are easy to create, but long annotations are awkward because space is limited. 
     Furthermore, people often organize their annotations and notes explicitly. Some writers use note cards, which can be flexibly sorted into different categories, to help them build connections between topics. Unfortunately, notecards require much effort to use. Information analysts often sort annotated paper into piles and some clip out useful sections with scissors and organize the clippings. 
     Once people reorganize information on paper, they often lose access to the original material. Notes are easier to work with than annotated documents, unless some information is missing. Similar problems arise with secondary notes and outlines that writers use to organize thoughts. There is a need for a free-form ink system that generates links between documents. 
     In Marquee, a real-time tool for video logging ( Marquee: A Tool For Real - Time Video Logging , Weber et al., In Proceedings of CHI &#39;94, ACM Press pp. 58-64, (1994) incorporated by reference herein in its entirety), a handwritten word could be circled to copy it to a palette of ink keywords, from which it could be dragged onto other pages. These ink keywords were later converted to text manually in order to support searching. Marquee, however, does not consider the shape of the ink keyword. Furthermore, Marquee&#39;s keywords do not act as links. Therefore, a user cannot select an instance of a keyword to view other instances of that keyword. 
     Although a later version of Marquee uses ink matching to highlight matching notes, ink matching was neither combined with the keywords nor used to create links ( Scribbler: A Tool For Searching Digital Ink , Poon et al. CHI &#39;95 short paper, (1995), incorporated by reference herein in its entirety). Other systems which have used ink matching have not supported links. 
     ConMentor supports ad-hoc linking and annotation on the Web. Users of ComMentor can annotate documents with a keyboard and a mouse, and can include them in a set by selecting from a list of sets ( Shared Web Annotations As A Platform For Third - Party Value - Added Information Providers: Architecture Protocols, And Usage Examples , Roscheisen et al., Technical Report STAN-CS-TR-97-1582, Stanford Integrated Digital Library Project, Computer Science Department, Stanford University (1995), incorporated by reference herein in its entirety). ComMentor, however, does not support free-form ink. 
     GO PenPoint includes a pen-based interface for manual linking. A link gesture creates a “button” that points to the current page. The button can then be dragged to another page to complete the link ( The Power of PenPoint , Carr et al., Addison-Wesley, Inc. (1991), incorporated by reference herein in its entirety). PenPoint supports free-form ink annotation but does not combine it with linking in any way. Co-Assigned U.S. patent application Ser. No. 08/929,426, filed Sep. 15, 1997, and incorporated herein in its entirety, discloses an active reading machine that creates links automatically from ink marks, but users do not have direct control over the target of the link. The system creates margin links and further reading lists that produce links via queries on the text, not ad-hoc links. 
     Co-assigned U.S. patent application Ser. No. 09/059,204, filed Apr. 14, 1998 and entitled “Method and Apparatus for Displaying References to a User&#39;s Document Browsing History within the Context of a New Document”, incorporated by reference herein in its entirety. That invention extracts portions from previously read documents and compares those portions to passages in a new document. Those passages in the new document which are identified as being closely related to a portion of a previously read document are provided with a selectable link to the portion in the previously read document. 
     Another co-assigned U.S. patent application Ser. No. 08/929,427, filed Sep. 15, 1997 and incorporated by reference herein in its entirety, discloses a system that extracts portions of a document that have been annotated with free-form ink and presents the annotation with their surrounding context in a separate view called a reader&#39;s notebook. The reader&#39;s notebook creates a special view with links to annotations, which could be considered a multi-way link. Although users of this system can specify which classes of annotations appear in the view, users cannot include or exclude specific annotations from the set. Furthermore, the links are based on properties that a user explicitly assigns to the ink by selecting a pen, rather than on the shape of the ink. 
     Yet another co-assigned U.S. patent application Ser. No. 08/821,311, filed on Mar. 20, 1997 and incorporated by reference herein in its entirety, discloses a system called Dynomite. Dynomite uses an ink index that organizes free-form ink notes in the same way that the reader&#39;s notebook organizes annotations ( Dynomite: A Dynamically Organized Ink and Audio Notebook , Wilcox et al., In Conference Proceedings of CHI &#39;97, ACM Press, pp. 186-193 (1997), incorporated by reference herein in its entirety). Dynomite also allows users to assign keywords to pages, and all the notes on the pages with those keywords can be grouped together. However, as with the reader&#39;s notebook, a user cannot include or exclude specific annotations from these groups, and links are based upon properties associated with the ink rather than on the shape of the ink. 
     Dolphin creates links to new pages from annotations that are marked with a “box” gesture ( DOLPHIN: Integrated Meeting Support Across Local and Remote Desktop Environments and Live Boards , Streitz et al., In Proceedings of the Conference on Computer Supported Cooperative Work, pp. 345-358 (1994), incorporated by reference herein in its entirety). These links are hierarchical, not ad-hoc. DOLPHIN does not allow users to specify arbitrary destinations for these links and treats a bookmark as a gesture and removes it after a link has been created. 
     The active reading machine disclosed in U.S. Patent Application Ser. Nos. 08/929,426, 08/929,427 supports reading and browsing over a wide variety of documents. Many of these documents were designed for presentation on paper and, therefore, lack hypertext links. One way to create a browsing environment is to automatically detect topics, references and other static document structure and then to generate the links automatically ( Automatic Hypertext Construction , Allan J., Ph.D. Thesis, Cornell University (1995), incorporated by reference herein in its entirety). Unfortunately, only a small fraction of all possible links are useful to a particular reader at a particular time and deciding on the right links ahead of time, without any knowledge of a reader&#39;s activities, is difficult. 
     A system that gives readers the tools for constructing links should be more useful than statically generated computer links because they can reflect a reader&#39;s idiosyncratic interests. At the same time, link construction should not interfere with a reader&#39;s primary activity of reading. However, conventional systems do not provide these features. 
     SUMMARY OF THE INVENTION 
     The invention enhances free-form ink annotating and note taking by creating ad-hoc links from free-form ink. People can use ad-hoc links to connect notes and outline entries to sources, or to group together the important passages on a particular topic. 
     Linking by inking may have a number of advantages over traditional link construction interfaces. First, ink is personal and idiosyncratic. People can use the flexibility of free-form ink to make anchors meaningful. Second, linking by inking is an extension of current practice. Readers already use ink marks on post-it notes or colored stick-ons and other types of annotations to characterize information efficiently. Third, because linking by inking requires no explicit interaction, people can create links more quickly and easily than with traditional interfaces where people must invoke a command and then browse for the target of the link. 
     Readers often link documents together for their own particular reasons. One typical practice is to mark places on different pages with the same circled symbol (e.g., the letter “A” or numeral “1”), thereby creating a logical link between them. The present invention creates “ink anchors” to help readers create idiosyncratic many-to-many links with minimal effort. Circling any mark converts that mark into an anchor. In this way, the system of this invention maintains multi-way links between similar ink anchors. 
     Ink anchors require relatively little effort to create. Readers can create links without selecting from a list, navigating or typing text. Readers merely create and use their own personal marks for the ink anchors. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of this invention will be described in detail, with reference to the following figures, wherein: 
     FIG. 1 is a block diagram of one embodiment of the electronic document reading system of this invention; 
     FIG. 2 shows a linked notebook view of this invention; 
     FIG. 3 shows another linked notebook view of this invention; 
     FIG. 4 shows a view of annotations-in-context for an ink anchor in accordance with this invention; 
     FIGS. 5A-5B is a flowchart outlining the control routine for generating ink anchors of one embodiment of a method of this invention; 
     FIGS. 6A-6B is a flowchart outlining the control routine of an erasing and link removal method of one embodiment of this invention; and 
     FIGS. 7A-7E show a flowchart outlining the control routine for generating links of one embodiment of a method of this invention. 
    
    
     These and other features and advantages of this invention are described in or are apparent from the following detailed description of the preferred embodiments. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows one embodiment of an electronic active reading system  10  of this invention. The electronic active reading system  10  includes a processor  12  communicating with a memory  14  that stores the program, documents and other data for practicing the invention. The processor  12  also communicates to a display  16 , keyboard  18 , a mouse  20  and a pen  22  via input/output device  24 . The keyboard  18 , mouse  20 , pen  22  and any other interface device (not shown) are operated by a user to control the operation of the electronic active reading system  10 . The display  16  may be on a stand-alone pen computer or a tablet connected by a tether to a conventional computer. 
     As shown in FIG. 1, the system  10  is preferably implemented using a programmed general purpose computer. However, the system  10  can also be implemented using a special purpose computer, a programmed microprocessor or microcontroller and any necessary peripheral integrated circuit elements, an ASIC or other integrated circuit, a hardwired electronic or logic circuit such as a discrete element circuit, a programmable logic device such as a PLD, PLA, FPGA or PAL, or the like. In general, any device on which a finite state machine capable of implementing the flowcharts shown in FIGS. 2 and 3 can be used to implement the system  10 . 
     Additionally, as shown in FIG. 1, the memory  14  is preferably implemented using static or dynamic RAM. However, the memory  14  can also be implemented using a floppy disk and disk drive, a writable optical disk and disk drive, a hard drive, flash memory or the like. Additionally, it should be appreciated that the memory  14  can be either distinct portions of a single memory or physically distinct memories. 
     Further, it should be appreciated that the links  26 ,  28 ,  30 ,  32  and  34  connecting the memory  14 , the display  16 , the keyboard  18 , the mouse  20  and the pen  22  to the processor  12  can be wired or wireless links to networks (not shown). These networks can be local area networks, wide area networks, intranets, the Internet, or any other distributed processing and storage networks. 
     As shown in FIG. 2, the present invention creates ad-hoc links from free-form ink to create a “linked notebook” that allows people to connect together their annotations, notes and outlines. The linked notebook allows writers to move quickly between their sources and their notes. Writers can copy material from their source to their notes to speed up note taking and avoid transcription errors. The linked notebook can also copy notes onto source documents in case the writer needs to re-read that source later. Additionally, the linked notebook allows people to organize and re-organize their notes onto pages, much as they would on paper, but without the effort of manual transcription. The invention also allows links between passages within the same document. 
     The linked notebook  40  displays a document  42  together with a notebook page  44 . This allows a reader to take notes  46  much as they would on paper. The linked notebook can also display three notebook pages  50 ,  52  and  54  side by side as shown in FIG.  3 . This provides a flexible way for people to prepare notes, transcribe notes onto pages on a particular topic, etc. 
     Users can build links  56  between documents simply by drawing a mark from a passage displayed in one window to a passage displayed in another window. Users can also copy text and ink from one document to another by circling and drawing a line to the destination. The copy  58  and the original  60  will be automatically linked together. Thus, annotations with surrounding text can be converted into notes. This is similar to the reader&#39;s notebook (discussed in the background), which lists clippings of annotated text, but here the presentation is directly under the user&#39;s control. People can also copy comments from the notebook onto the document (not shown). 
     As shown in FIG. 4, the present invention also creates ad-hoc links from free-form ink to create ink anchors  62  which may be multi-way links between matching marks  64  to help people categorize their annotations and notes. Ink anchors  62  help readers create idiosyncratic many-to-many links with minimal effort. Circling any mark  64  converts that mark into an ink anchor  62 . The system computes links between the ink anchors by grouping ink marks together that have similar morphological or spatial characteristics. 
     Ink anchors  62  require relatively little effort to create. Readers are able to create links without selecting from a list, navigating or by typing text. They merely need to recreate their own, personal marks, although readers may forget anchors that they use infrequently, this is preferable to alternatives such as presenting readers with a large number of choices every time they build a link. 
     As shown in FIG. 4, tapping on a source ink anchor  62  produces a list of clippings  66  that contain matching target ink anchors  62 . This view  66  shows clippings of documents that correspond to annotations made by the reader. The clippings  68  include enough context to make the ink marks meaningful, but still present a concise view of the annotated documents. 
     Clippings  68  include nearby annotations, and therefore, may show multiple ink anchors  62  in the same clipping. This allows readers to observe connections between different sets of ink anchors  62  without following the links. 
     The present invention also helps a reader remember the “names” they have been using for the links by providing a list of clippings  68  over all ink anchors  62 , sorted by time (not shown). A user preference provides that the view may only contain the most recent occurrence of each ink anchor  62 . 
     The ink anchors of this invention may be implemented in an active reading machine that runs on Windows 95/NT, uses the Win 32 API, and is implemented in C++. The system of this invention can take over the entire display, and may avoid using Windows widgets. Instead, the system of this invention can display a small set of widgets, render them to an in-memory bitmap, rotate the bitmap, and copy it to a display device. In this way, the system of this invention can use a landscape device in portrait mode. 
     One embodiment of the system of this invention uses an “image plus text” file format. With this format, the system can handle most digital documents, and also documents that came to the user on paper. The text, inferred from print commands or from optical character recognition applied to the scanned image, is tied to the image by a bounding rectangle (in pixels) for each word. This text is intended to support information retrieval, but is not shown to the reader directly. In principle, the “image plus text” file format lets users load documents into the system of this invention easily, by “printing” or by scanning. 
     The system of the invention uses several data structures. An ink point is a two-dimensional coordinate. An ink stroke is a sequence of ink points and a location in a document such as a page number. An ink annotation database stores ink strokes with several operations such as add a stroke, remove a stroke and look up strokes corresponding to a region in a document. An ink anchor is one or more ink strokes, not including the ink anchor circle. An ink matching database stores ink anchors with several operations such as add an ink anchor, delete an ink anchor and look for an ink anchor which matches some ink strokes. A link target is a region in a document and one or more ink strokes. A link is an ink anchor and at least one link target. A link database stores links with several operations such as lookup a link corresponding to an ink anchor, lookup a link target that corresponds to a location in a document, lookup a link target that corresponds to a stroke and lookup a link that corresponds to a link target. 
     FIGS. 5A-7E show control routines for various procedures of the present invention. Each of the control routines may operate within another higher level control routine. While each of the control routines in FIGS. 5A-7E indicate that these control routines stop, it is to be understood that control may be returned to another or higher level control routine after that control routine stops. 
     FIGS. 5A-5B show a flowchart of a control routine for creating a link. The control routine starts at step S 100  and continues to step S 110 . In step S 110 , the control routine determines whether a “pen down” has been detected. If a “pen down” has not been detected the control routine returns to step S 110 . If a “pen down” has been detected, in step S 110 , the control routine continues to step S 120 . 
     In step S 120 , the control routine adds a stroke and continues to step S 130 . In step S 130 , the control routine determines if a “pen up” has been detected. If in step S 130 , a “pen up” has not been detected, the control routine returns to step S 120 . If in step S 130 , a “pen up” has been detected the control routine continues to step S 140 . 
     In step S 140 , the control routine updates the display to show the strokes that have been newly added. The control routine then continues to step S 150 , where the control routine determines whether the added stroke(s) includes a circle. If in step S 150 , the control routine determines that the added stroke(s) is not a circle, then the control routine jumps to step S 260  where the control routine stops. If in step S 150 , the control routine determines that the added stroke(s) is a circle, the control routine continues to step S 160 . 
     In step S 160 , the control routine determines whether an ink stroke exists in the circle. If in step S 160 , the control routine determines that an ink stroke does not exist in the circle then the control routine jumps to step S 260 . If in step S 160 , the control routine determines that an ink stroke is in the circle then the control routine continues to step S 170 . 
     In step S 170 , the control routine determines whether there is a matching ink stroke inside the ink anchor circle in the ink matching database. The control routine compares the morphological or spatial characteristics to determine if a match exists. If in step S 170 , there is no matching ink stroke then the control routine continues to step S 180 . 
     In step S 180 , the control routine creates a new ink anchor and continues to step S 190 . In step S 190 , the control routine adds the new ink anchor to the ink matching database and continues to step S 200 . In step S 200 , the control routine creates a new link based upon the ink anchor and continues to step S 210 . In step S 210 , the control routine adds the new link to the link database and continues to step S 230 . 
     In step S 170 , if the control routine determines that a matching ink anchor exists then the control routine continues to step S 220 . In step S 220 , the control routine determines which link corresponds to the matching ink anchor and continues to step S 230 . 
     In step S 230 , the control routine creates a new link target and continues to step S 240 . In step S 240 , the control routine adds strokes to the new link target and continues to step S 250 . In step S 250 , the control routine adds the new link target to the link and continues to step S 260  where the control routine stops. 
     The system of this invention follows a link by detecting a tap with a pen on a link target and looking up the link target that corresponds to the location of the tap using the link database. If the link database includes a link that corresponds to the location of the tap then the control routine of the system determines a corresponding link in the link database. The control routine then displays the list of link targets as “annotations in context” as is shown for example in FIG.  4 . The user may then select a clipping of an annotation in context to view a particular link target. 
     A user can remove an unintended ink anchor by erasing the anchor. Therefore, the user can correct erroneous ink anchor matches by erasing the anchor, rewriting the ink, and circling it again. 
     FIGS. 6A and 6B show a flowchart detailing a control routine for erasing and removing a link. The control routine starts at step S 300 , and continues to step S 310 . In step S 310 , the control routine determines whether an eraser has been selected. If in step S 310 , the control routine determines that an eraser has not been selected then the control routine jumps to step S 420  where the control routine of FIGS. 6A and 6B ends. If in step S 310 , the control routine determines that an eraser has been selected, the control routine continues to step S 320 . 
     In step S 320 , the control routine determines whether a “pen tap” (or other selection) has been detected. If in step S 320 , the control routine determines that a “pen tap” has not been detected, then the control routine returns to step S 320 . If in step S 320 , the control routine determines that a “pen tap” has been detected, then the control routine continues to step S 330 . 
     In step S 330 , the control routine determines whether an ink stroke corresponds to the location of the “pen tap” in the annotation database. If in step S 330 , the control routine determines that no ink stroke matches the “pen tap” location, the control routine returns to step S 320 . If in step S 330 , the control routine determines that an ink stroke matching the “pen tap” location exists in the annotation database then the control routine continues to step S 340 . 
     In step S 340  the control routine determines whether there is a link target in the link database that corresponds to the ink stroke. If in step S 340 , the control routine determines that there is no link target that corresponds to the ink stroke then the control routine continues to step S 350 . In step S 350 , the control routine removes the stroke from the ink annotation database and continues to step S 410 . If in step S 340 , the control routine determines that a link target in the link database does correspond to the ink stroke then the control routine continues to step S 360 . 
     In step S 360 , the control routine removes all ink strokes in the link target from the ink annotation database and continues to step S 370 . In step S 370 , the control routine removes the link target from the link and continues to step S 380 . In step S 380 , the control routine determines if the link is empty. If in step S 380 , the control routine determines that the link is not empty the control routine jumps to step S 410 . If in step S 380 , the control routine determines that the link is empty then the control routine continues to step S 390 . 
     In step S 390 , the control routine removes the link&#39;s ink anchor from the ink matching database and continues to step S 400 . In step S 400 , the control routine removes the link from the link database and continues to step S 410 . In step S 410 , the control routine updates the display and continues to step S 420  where the control routine stops. 
     One embodiment of the linked notebook of this invention generates a two-way link from an ink stroke that crosses at least one window. The spatial characteristics of ink strokes allow the system to determine if an ink stroke crosses a window boundary. The spatial characteristics of an ink stroke include, for example, two-dimensional position information, location information within a document such as section page or chapter location and/or window position. The system of this invention creates a separate segment each time an ink stroke crosses a window boundary and the segments other than the first and last segment do not act as links. 
     The linked notebook system of this invention uses several additional data structures. A window is a region on the display that is dedicated to a particular view such as a page in a notebook or document. A window manager stores the current set of windows on the display with several operations such as look up a view and a location from a position on display, display a new view to the side of a specified existing view and interpolate a sequence of two-dimensional locations in views from a line (a pair of points) on the display by adding two points at each window boundary (one on each view). A copied region is a stroke, a region in a source view and a location in a target view. 
     FIGS. 7A-7E show a flowchart detailing a control routine for the link creation process for links that extend across windows. The control routine starts at step S 500  and continues to step S 510 . At step S 510 , the control routine determines whether a “pen down” has been detected. If in step S 510 , the control routine determines that a “pen down” has not been detected the control routine returns to step S 510 . If in step S 510 , the control routine determines that a “pen down” has been detected then the control routine continues to step S 520 . 
     In step S 520 , the control routine sets the last-display-point to the position of the pen and continues to step S 530 . In step S 530 , the control routine looks up the last-view for the last-displayed-point using the window manager and continues to step S 540 . In step S 540 , the control routine looks up the last-location for the last-display-point using the window manager and continues to step S 550 . In step S 550 , the control routine creates a new stroke on the last-view starting at the last-location using the ink annotation database and continues to step S 560 . 
     In step S 560 , the control routine sets the stroke-sequence to the new stroke and continues to step S 570 . In step S 570 , the control routine updates the display and continues to step S 580 . In step S 580 , the control routine determines whether a “pen up” has been detected. If in step S 580 , a “pen up” has been detected then the control routine jumps to step S 720 . If in step S 580 , the control routine does not detect a “pen up” then the control routine continues to step S 590 . 
     In step S 590 , the control routine sets the new-display-point to the position of the pen and continues to step S 600 . In step S 600 , the control routine interpolates a sequence of locations in views from the line from the last-display-point to the new-display-point using the window manager and continues to step S 610 . In step S 610 , the control routine sets the last-display-point to the new-display-point and continues to step S 620 . 
     In step S 620 , the control routine determines whether there are more views in the sequence of locations. If in step S 620 , the control routine determines that there are no more views than the control routine continues to step S 630 . In step S 630 , the control routine updates the display and continues to step S 640 . In step S 640 , the control routine gets the new pen location and returns to step S 580 . 
     If the control routine determines, in step S 620 , that more views exist then the control routine continues to step S 650 . In step S 650 , the control routine determines whether there are more locations in the view. If in step S 650 , the control routine determines that there are no more locations than the control routine jumps to step S 710 . 
     If in step S 650 , the control routine determines that there are more locations then the control routine continues to step S 660 . In step S 660 , the control routine determines whether the view equals the last-view. If in step S 660 , the control routine determines that the view does equal the last-view then the control routine continues to step S 670 . In step S 670 , the control routine adds a location to the stroke and jumps to step S 700 . If in step S 660 , the control routine determines that the view does not equal the last-view then the control routine continues to step S 680 . 
     In step S 680 , the control routine creates a new stroke on the view starting at the location using the ink annotation database and continues to step S 690 . In step S 690 , the control routine adds the new stroke to the stroke-sequence and continues to step S 700 . In step S 700 , the control routine sets the last-location to the current location and continues to step S 710 . In step S 710 , the control routine sets the last-view to the current view and returns to step S 620 . 
     In step S 720 , the control routine determines whether the stroke-sequence contains more than one stroke. If in step S 720 , the control routine determines that the stroke-sequence does not contain more than one stroke then the control routine jumps to step S 810 . If in step S 720 , the control routine determines that the stroke-sequence contains more than one stroke, then the control routine continues to step S 730 . 
     In step S 730 , the control routine sets the source-view to the view of the first stroke in the sequence and continues to step S 740 . In step S 740 , the control routine sets the target-view to the view of the final stroke in the sequence and continues to step S 750 . 
     In step S 750 , the control routine determines if the target-view equals the source view. If the target-view equals the source view than the control routine jumps to step S 810 . If in step S 750 , the control routine determines that the target-view does not equal the source view then the control routine continues to step S 760 . 
     In step S 760 , the control routine creates a new link from the stroke-sequence using the link database and continues to step S 770 . In step S 770 , the control routine determines whether a region has been selected by the first stroke. In step S 770 , if no region has been selected then the control routine jumps to step S 810 . In step S 770 , if the control routine determines that a region has been selected then the control routine continues to step S 780 . 
     In step S 780 , the control routine gets the region that has been selected by the initial portion of the first stroke in the sequence and continues to step S 790 . In step S 790 , the control routine adds a copied region to the link that includes the first stroke, the region and the final location in the final stroke and continues to step S 800 . In step S 800 , the control routine updates the display and continues to step S 810  where the control routine stops. 
     The system of the invention displays ink strokes across multiple windows when not all the windows are displayed by truncating the ink stroke. In other words, the system shows the ink stroke only where it was originally visible. 
     Additionally, the system of the invention may highlight ink strokes to indicate whether it acts as a link or not. For instance, the system of the invention may show ink strokes in gray which correspond to links to windows or pages which are not visible and may bold or use a different color for ink strokes which correspond to links to windows or pages which are visible. 
     Free-form ink annotation is intended to mean a visible ink stroke of arbitrary shape made with a pointing device that persists over time. The system infers some meaning from the shape or morphological characteristics of the ink stroke but does remove the ink stroke once it is recognized. 
     It is to be understood that the term document is intended to include text, video, audio and any other combination of media. Further, it is intended to be understood that the term text is intended to include text, digital ink, audio, video or any other content of a document to include the document&#39;s structure. It is also intended to be understood that ad-hoc links are links that are generated in response to and based upon a user&#39;s input of free-form ink rather than a link that is automatically generated such as hierarchical links or query-mediated links. 
     While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations are apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention.