METHOD AND SYSTEM FOR NAVIGATING A DIRECTORY

Abstract: A method and system for enabling navigation of a directory. The method includes printing a document containing a list of directory entries corresponding to at least one node of an index of the directory, with at least one user interactive element which enables a user to indicate a request for further directory information by interacting with the element using a sensing device which is adapted to transmit request data to a computer system; and printing the further directory information on a document.

Description: METHOD AND SYSTEM FOR NAVIGATING A DIRECTORY FIELD OF INVENTION The present invention relates generallv to methods, systems and apparatus for interacting with computers by means of printed matter and sensing devices More particularK the invention relates to director, navigation utilizing such methods systems and apparatus The invention has been developed primaπh to allow a large number of distributed users to interact with networked information via pπnted matter and to obtain interactive printed matter on demand \ ta high-speed networked color printers Although the invention will largely be described herein with reference to this use it will be appreciated that the invention is not limited to use in this field CO-PENDING APPLICATIONS Various methods systems and apparatus relating to the present invention are disclosed in the following co- pending applications filed by the applicant or assignee of the present invention simultaneously with the present application PCT/AU00/00518, PCT/AU00/00519, PCT/AU00/00520 PCT/AUOO/00521, PCT/AUOO/00523, PCT/AU00/00524, PCT/AU00/00525, PCT/AU00/00526, PCT/AU00/00527, PCT/AUOO/00528, PCT/AU00/00529, PCT/AUOO/00530, PCT/AU00/00531 , PCT/AU00/00532, PCT/AU00/00533, PCT/AU00/00534, PCT/AU00/00535, PCT/AU00/00536, PCT/AU00/00537, PCT/AUOO/00538, PCT/AU00/00539, PCT/AU00/00540, PCT/AU00/00541 , PCT/AU00/00542, PCT/AU00/00543, PCT/AU00/00544, PCT/AU00/00545, PCT/AU00/00547, PCT/AU00/00546, PCT/AU00/00554, PCT/AU00/00556, PCT/AUOO/00557, PCT/AUOO/00558, PCT/AU00/00559, PCT/AU00/00560, PCT/AUOO/00561 , PCT/AU00/00562, PCT/AUOO/00563, PCT/AU00/00564, PCT/AU00/00566, PCT/AU00/00567, PCT/AUOO/00568, PCT/AU00/00569, PCT/AU00/00570, PCT/AU00/00571 , PCT/AUOO/00572. PCT/AU00/00573, PCT/AU00/00574, PCT/AU00/00575, PCT/AU00/00576, PCT/AU00/00577, PCT/AU00/00578, PCT/AU00/00579, PCT/AUOO/00581, PCT/AU00/00580, PCT/AU00/00582, PCT/AU00/00587, PCT/AU00/00588, PCT/AU00/00589, PCT/AUOO/00583, PCT/AU00/00593, PCT/AU00/00590, PCT/AU00/00591, PCT/AU00/00592, PCT/AU00/00594, PCT/AU00/00595, PCT/AU00/00596, PCT/AU00/00597, PCT/AU00/00598, PCT/AU00/00516, and PCT/AU00/00517 The disclosures of these co-pending applications are incorporated herein by cross-reference BACKGROUND Paper is widely used to display and record information Printed information is easier to read than information displayed on a computer screen Hand-drawing and handwπting afford greater richness of expression than input via a computer keyboard and mouse Moreover, paper doesn't run on batteries, can be read in bright light, more robustly accepts coffee spills, and is portable and disposable Online publication has many advantages over traditional paper-based publication From a consumer's point of view, information is available on demand, information can be navigated via hypertext links searched and automatically personalized - 1 a - From the publisher's point of view, the costs of printing and physical distribution are eliminated, and the publication becomes more attractive to the advertisers who pa for it because it can be targeted to specific demographics and linked to product sites Online publication also has disadvantages Computer screens are inferior to paper At the same quality as a magazine page, an SVGA computer screen displays onl> about a fifth as much information Both CRTs and LCDs have brightness and contrast problems, particularly when ambient light is strong, while ink on paper, being reflective rather than emissive, is both bright and sharp in ambient light OBJECT It is an object of the invention to combine ad\ antages of pπnted and online information, to facilitate quick and easy onlme directory navigation via a pnnted document SUM MARY OF INVENTION In accordance with the invention, there is provided a method of enablmg navigation of a directory mcludmg pnntmg a document containing a list of directorv entnes coπesponding to at least one node of an mdex of the directory with at least one user interactπ e element which enables a user to mdicate a request for further directory information by mteracting with the element usmg a sensmg device which is adapted to transmit request data to a computer s\ stem and pnntmg the further directory information on a document Preferably, the further directory information includes a list of entnes coπesponding to at least one further node of the mdex and for example, mteracting with the at least one user mteractive element corresponds to an operation of moving to one of a first, previous, next or last node m the mdex Most preferably the further directory information is pnnted on a double-sided page Alternatively the further directory information mcludes a list of further nodes m the directory index Preferab mteracting with the at least one user mteractive element coπesponds to an operation of one of movmg to one of a parent, child or root node of the mdex The or another element may mstead or additionally, be used to facilitate searching of the directory The method preferably mcludes usmg the sensing device to select an individual entry m the list, the selection bemg identified m the computer system to facilitate pnntmg of details of the corresponding index node or directory object Preferably, the document mcludes coded data indicative of an identity of the document and of the at least one mteractive element, and wherein the method mcludes receiving, m the computer system, mdicatmg data from the sensmg device regarding the identity of the document and a position of the sensmg device relative to the document in order to identify the document and determine when the sensmg device is used to interact with the element The method may further include receivmg, m the computer svstem, movement data regarding movement of the sensing device relative to the document, with the sensing device preferably sensmg its movement relative to the document using at least some of the coded data, and identifying the request in the computer svstem trom the movement being at least partially withm a zone associated with the mteractive element Preferably, the sensmg device includes an identification code specific to a particular user and the method mcludes momtoπng use ol the sensmg device in the computer system The method may further mclude pnntmg the information on a surface ol a s-trface-defii-mg structure and at the same time, pπnting the coded data on the surface, with the coded data preferably being substantially invisible m the visible spectrum Prelerablv, the method includes retaining a retnevable record of the pnnted document, the document being retnevable using the identity data as contained m the coded data In another aspect, there is provided a system lor enabling navigation of a directory, mcludmg a computer system for formatting a document with a list of directory entries corresponding to at least one node of an index of the directory and at least one user mteractive element to enable a user to request further duectorv information a pπnter for pnntmg the document, and a sensmg device for mteractmg with the element and transmitting request data to the computer svstem to facilitate the further information being sent from the computer svstem to the pnnter lor pnntmg m a further document - 3 - Preferably, the further directorv information mcludes a list ol entnes corresponding to at least one further node of the mdex Most preferably, the further duectory information is pnnted on a double-sided page Alternatively, the further directory information mcludes a list of further nodes m the directory . m which case the element may be associated with an operation of movmg to one of a parent, child or root node of the mdex The or another element may mstead or additionally be associated with a search function to facilitate searching of the directory Preferably, the document mcludes coded data indicative of an identity of the document and of the at least one mteractive element The system preferably further mcludes the sensmg device being adapted to select an individual entry m the document and the computer system is arranged to send details of the corresponding mdex node or directorv object to the pnnter for pnntmg The computer system is preferably adapted to receive movement data regarding movement of the sensmg device relative to the document, and interpret said movement of the sensmg device as it relates to said at least one element More preferably, the sensmg device senses its own movement relative to the document usmg the coded data The sensing device may mclude an identification code specific to a particular user to allow the computer system to monitor the use of the sensmg device The sensmg device preferably also mcludes a marking mb The pnnter is preferably arranged to pnnt the coded data on demand, at the same time as pnntmg the document on the s-uface-defirung structure, with the coded data preferably bemg substantially invisible m the visible spectrum The svstem preferably mcludes a database for keeping a retnevable record of each document generated, each document bemg retnevable by usmg its identity, as mcluded m its coded data BRIEF DESCRIPTION OF DRAWINGS Prefeπed and other embodiments of the invention will now be descnbed, by way of non-limiting example only, with reference to the accompanying drawings, in which Figure 1 is a schematic of a the relationship between a sample pnnted netpage and its online page descnption, Figure 2 is a schematic view of a interaction between a netpage pen, a netpage pnnter, a netpage page server, and a netpage application server, Figure 3 illustrates a collection of netpage servers and pnnters interconnected via a network, Figure 4 is a schematic view of a high-level structure of a pnnted netpage and its onlme page descπption, Figure 5 is a plan view showing a structure of a netpage tag, Figure 6 is a plan view showing a relationship between a set of the tags shown m Figure 5 and a field of view of a netpage sensmg device m the form of a netpage pen, Figure 7 is a flowchart of a tag image processing and decoding algonthm. Figure 8 is a perspective view of a netpage pen and its associated tag-sensing field-of-view cone, Figure 9 is a perspective exploded view of the netpage pen shown in Figure 8. Figure 10 is a schematic block diagram of a pen controller for the netpage pen shown m Figures 8 and 9, Figure 11 is a perspective view of a wall-mounted netpage pnnter. Figure 12 is a section through the length of the netpage pnnter of Figure 11 , Figure 12a is an enlarged portion of Figure 12 showing a section of the duplexed pnnt engines and glue wheel assembly, Figure 13 is a detailed view of the ink cartndge, ink, air and glue paths, and pnnt engines of the netpage pnnter of Figures 1 1 and 12, Figure 14 is a schematic block diagram ol a pnnter controller for the netpage pπnter shown in Figures 11 and 12. Figure 15 is a schematic block diagram of duplexed pnnt engme controllers and Memjet™ prmtheads associated with the pnnter controller shown m Figure 14, Figure 16 is a schematic block diagram of the pnnt engme controller shown m Figures 14 and 15. Figure 17 is a perspective view of a smgle Memjet™ pπnting element, as used m, for example, the netpage pnnter of Figures 10 to 12, Figure 1 is a perspective view ol a small part of an array of Memjet™ pnntmg elements. Figure 19 is a senes of perspective views illustrating the operating cycle of the Memjet™ pnntmg element shown in Figure 13, Figure 20 is a perspective view of a short segment of a pagewidth Memjet™ pnnthead Figure 21 is a schematic view of a user class diagram, Figure 22 is a schematic view of a pnnter class diagram, Figure 23 is a schematic view of a pen class diagram. Figure 24 is a schematic view of an application class diagram, Figure 25 is a schematic view of a document and page descnption class diagram, Figure 26 is a schematic view of a document and page ownership class diagram Figure 27 is a schematic view of a terminal element specialization class diagram, Figure 28 is a schematic view of a static element specialization class diagram, Figure 29 is a schematic view of a hyperlink element class diagram, Figure 30 is a schematic view of a hyperlink element specialization class diagram, Figure 31 is a schematic view of a hyperlmked group class diagram, Figure 32 is a schematic view of a form class diagram, Figure 33 is a schematic view of a digital ink class diagram, Figure 34 is a schematic view of a field element specialization class diagram, Figure 35 is a schematic view of a checkbox field class diagram, Figure 36 is a schematic view of a text field class diagram, Figure 37 is a schematic view of a signature field class diagram, Figure 38 is a flowchart of an input processmg algonthm, Figure 38a is a detailed flowchart of one step of the flowchart of Figure 38. Figure 39 is a schematic view of a page server command element class diagram, Figure 40 is a schematic view of a resource descnption class diagram, Figure 41 is a schematic view of a favontes list class diagram, Figure 42 is a schematic view of a history list class diagram, Figure 43 is a schematic view of a subscnption delivery protocol, Figure 44 is a schematic view of a hyperlink request class diagram, Figure 45 is a schematic view of a hyperlink activation protocol, Figure 46 is a schematic view of a form submission protocol, Figure 47 is a schematic view of a commission payment protocol, Figure 48 is a schematic view of a set of user interface flow document icons, Figure 49 is a schematic view of a set of user interface page layout element icons, Figure 50 is a schematic view of a indexed directory class diagram, Figure 51 is a schematic view of a geneπc directorv mdex page, and Figure 52 is a schematic view of a directory navigation user interface flow - 5 - DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS Note Memiet™ is a trade mark of Silverbrook Research Pty Ltd, Australia In the preferred embodiment, the invention is configured to work w th the netpage networked computer system, a detailed overview of which follows It will be appreciated that not every implementation will necessaπlv embody all or even most of the specific details and extensions discussed below m relation to the basic svstem However, the svstem is descπbed in its most complete form to reduce the need for external reference when attempting to understand the context m which the preferred embodiments and aspects of the present invention operate In bnef summary, the preferred form of the netpage system emplovs a computer interface m the form of a mapped surface, that is, a physical surface which contams references to a map of the surface mamtamed m a computer system The map references can be quened by an appropnate sensmg device Depending upon the specific implementation, the map references may be encoded visibly or invisibly , and defined in such a way that a local query on the mapped surface yields an unambiguous map reference both withm the map and among different maps The computer system can contain information about features on the mapped surface, and such information can be retneved based on map references supplied by a sensmg device used with the mapped surface The lntormation thus retneved can take the form of actions which are initiated by the computer svstem on behalf of the operator m response to the operator's interaction with the surface features In its prefeπed form, the netpage system relies on the production ol. and human interaction with, netpages These are pages of text, graphics and images pnnted on ordinary paper, but which work like interactive web pages Information is encoded on each page usmg ink which is substantially invisible to the unaided human eye The ink, however, and thereby the coded data, can be sensed by an optically imaging pen and transmitted to the netpage system In the preferred form, active buttons and hyperlinks on each page can be clicked with the pen to request information from the network or to signal preferences to a network server In one embodiment, text wntten by hand on a netpage is automatically recognized and converted to computer text m the netpage system, allowing forms to be filled m In other embodiments, signatures recorded on a netpage are automatically venfied. allowing e-commerce transactions to be securelv authorized As illustrated in Figure 1 , a pπnted netpage 1 can represent a interactive form which can be filled m by the user both physicalh, on the pnnted page, and "electronically", via communication between the pen and the netpage system The example shows a "Request" form containing name and address fields and a submit button The netpage consists of graphic data 2 pπnted usmg visible ink, and coded data 3 pnnted as a collection of tags 4 usmg invisible mk The corresponding page descnption 5, stored on the netpage network, descnbes the individual elements of the netpage In particular it descnbes the type and spatial extent (zone) of each interactive element (l e text field or button m the example), to allow the netpage svstem to correctly interpret input via the netpage The submit button 6, for example, has a zone 7 which coπesponds to the spatial extent of the corresponding graphic 8 As illustrated m Figure 2, the netpage pen 101, a preleπed form of which is shown m Figures 8 and 9 and descnbed in more detail below, works m conjunction w th a netpage pnnter 601, an Internet-connected pnntmg appliance lor home, office or mobile use The pen is wireless and communicates securely with the netpage pπnter via a short-range radio link 9 The netpage pnnter 601 , a preferred form of which is shown m Figures 11 to 13 and descnbed m more detail below, is able to deliver, penodically or on demand, personalized newspapers, magazines, catalogs, books and other publications, all pnnted at high quality as mteractive netpages Unlike a personal computer, the netpage pnnter is an appliance which can be, for example, wall-mounted adjacent to an area where the morning news is first consumed, such as m a user's kitchen, near a breakfast table, or near the household s pomt of departure for the day It also comes m - 6 - tabletop desktop, portable and miniature versions Netpages pnnted at their pomt of consumption combme the ease-of-use oi paper with the timeliness and interactivity of an mteractive medium As shown m Figure 2, the netpage pen 101 mteracts with the coded data on a pnnted netpage 1 and communicates, via a short-range radio link 9, the mteraction to a netpage pnnter The pnnter 601 sends the mteraction to the relevant netpage page server 10 for interpretation In appropnate circumstances, the page server sends a coπesponding message to application computer software nmnmg on a netpage application server 13 The application server may in turn send a response which is pnnted on the ongmating pnnter The netpage system is made considerably more convement m the preferred embodiment by bemg used m conjunction with high-speed microelectromechamcal system (MEMS) based inkjet (Memjet™) pnnters In the preferred form of this technology, relatively high-speed and high-quality pnntmg is made more affordable to consumers In its prefeπed form, a netpage publication has the physical characteπstics of a traditional newsmagazme, such as a set of letter-size glossy pages pnnted m full color on both sides, bound together lor easy navigation and comfortable handling The netpage pnnter exploits the growing availability of broadband Internet access Cable service is available to 95% of households m the United States, and cable modem service offering broadband Internet access is already available to 20% of these The netpage pnnter can also operate with slow er connections but with longer delivery times and lower image quality Indeed, the netpage system can be enabled usmg existing consumer inkjet and laser pnnters, although the system will operate more slowly and will therefore be less acceptable from a consumer's pomt of view In other embodiments, the netpage system is hosted on a pnvate intranet In still other embodiments, the netpage system is hosted on a smgle computer or computer-enabled device, such as a pnnter Netpage publication servers 14 on the netpage network are configured to deliver print-quality publications to netpage pnnters Penodical publications are delivered automatically to subscnbmg netpage pnnters via pointcasting and multicasting Internet protocols Personalized publications are filtered and formatted according to individual user profiles A netpage pnnter can be configured to support any number of pens, and a pen can work with any number of netpage pnnters In the prefeπed implementation, each netpage pen has a unique identifier A household may have a collection ol colored netpage pens, one assigned to each member of the family This allows each user to maintain a distinct profile with respect to a netpage publication server or application server A netpage pen can also be registered with a netpage registration server 11 and linked to one or more payment card accounts This allows e-commerce payments to be securely authorized usmg the netpage pen The netpage registration server compares the signature captured by the netpage pen with a previously registered signature, allowing it to authenticate the user's identity to an e-commerce server Other biometncs can also be used to venfy identity A version of the netpage pen mcludes fingerpnnt scanning, venfied m a similar way by the netpage registration server Although a netpage pπnter may deliver penodicals such as the morning newspaper without user intervention, it can be configured never to deliver unsolicited junk mail In its preferred form, it only delivers penodicals from subscnbed or otherwise authorized sources In this respect the netpage pnnter is unlike a fax machine or e-mail account which is visible to any junk mailer who knows the telephone number or email address 1 NETPAGE SYSTEM ARCHITECTURE Each object model m the system is descnbed usmg a Unified Modeling Language (UML) class diagram A class diagram consists of a set of object classes connected by relationships, and two lands of relationships are of mterest here associations and generalizations An association represents some kind of relationship between objects l e between instances of classes A generalization relates actual classes, and can be understood m the following wav li a class is - 7 - thought of as the set of all obiects of that class and class A is a generalization of class B then B is sunplv a subset of A The UML does not directly support second-order modelling - 1 e classes of classes Each class is drawn as a rectangle labelled with the name of the class It contams a list of the attnbutes of the class, separated from the name by a honzontal lme, and a list of the operations of the class, separated from the attribute list by a honzontal lme In the class diagrams which follow, however, operations are never modelled An association is drawn as a lme joining two classes, optionally labelled at either end with the multiplicity of the association The default multiplicity is one An astensk (*) mdicates a multiplicity of "many", l e zero or more Each association is optionally labelled with its name, and is also optionally labelled at either end with the role of the correspondmg class An open diamond mdicates an aggregation association ( is-part-of ), and is drawn at the aggregator end of the association lme A generalization relationship ("ls-a") is drawn as a solid lme )oιmng two classes, with an aπo (m the form of an open tnangle) at the generalization end When a class diagram is broken up into multiple diagrams, an\ class which is duplicated is shown with a dashed outline in all but the mam diagram which defines it It is shown with attributes onlv where it is defined 1.1 NETPAGES Netpages are the foundation on which a netpage network is built They provide a paper-based user interlace to published information and mteractive services A netpage consists of a pnnted page (or other surface region) invisibly tagged with references to an online descnption of the page The onlme page descnption is mamtamed persistently by a netpage page server The page descnption descnbes the visible layout and content of the page, mcludmg text, graphics and images It also descπbes the mput elements on the page, mcludmg buttons, hyperlinks, and mput fields A netpage allows markings made with a netpage pen on its surface to be simultaneously captured and processed by the netpage svstem Multiple netpages can share the same page descnption However, to allow mput through otherwise identical pages to be distinguished, each netpage is assigned a unique page identifier This page ID has sufficient precision to distinguish between a very large number of netpages Each reference to the page descnption is encoded m a pnnted tag The tag identifies the unique page on which it appears, and thereby indirectly identifies the page descnption The tag also identifies its own position on the page Charactenstics of the tags are descnbed m more detail below Tags are pnnted m infrared-absorptive mk on any substrate which is infrared-reflective, such as ordinarv paper Near-infrared wavelengths are invisible to the human eye but are easily sensed by a solid-state image sensor with an appropnate filter A tag is sensed by an area image sensor in the netpage pen, and the tag data is transmitted to the netpage system via the nearest netpage pnnter The pen is wireless and communicates with the netpage pnnter via a short-range radio link Tags are sufficiently small and densely arranged that the pen can reliably image at least one tag even on a smgle click on the page It is important that the pen recognize the page ED and position on every mteraction with the page, smce the mteraction is stateless Tags are eπor-coπectably encoded to make them partially tolerant to surface damage The netpage page server maintains a unique page instance for each pnnted netpage, allowing it to maintain a distinct set of user-supplied values for mput fields m the page descnption for each pnnted netpage The relationship between the page descnption, the page instance, and the pnnted netpage is shown m Figure 4 The page instance is associated with both the netpage pnnter which pnnted it and, if known, the netpage user who requested it - 8 - 1.2 NETPAGE TAGS 1.2.1 Tag Data Content In a preferred form, each tag identifies the region m which it appears, and the location of that tag withm the region A tag may also contam flags which relate to the region as a whole or to the tag One or more flag bits may, for example, signal a tag sensmg device to provide feedback mdicative of a function associated with the immediate area of the tag, without the sensing device havmg to refer to a descnption of the region A netpage pen may, for example, llluπunate an "active area" LED when m the zone of a hyperlink As will be more clearly explamed below, m a preferred embodiment, each tag contams an easily recognized mvanant structure which aids initial detection, and which assists in minimizing the effect of any warp mduced by the surface or by the sensmg process The tags preferably tile the entire page, and are sufficiently small and densely arranged that the pen can reliably image at least one tag even on a single click on the page It is important that the pen recogmze the page ID and position on every mteraction with the page since the interaction is stateless In a preferred embodiment, the region to which a tag refers coincides with an entire page, and the region ID encoded m the tag is therefore synonymous with the page ID of the page on which the tag appears In other embodiments the region to which a tag refers can be an arbitrary subregion of a page or other surface For example, it can coincide with the zone of an mteractive element m which case the region ID can directly identify the mteractive element Table 1 - Tag data Each tag contams 120 bits of information, typically allocated as shown in Table 1 Assuming a maximum tag density of 64 per square inch, a 16-bit tag ID supports a region size of up to 1024 square mches Larger regions can be mapped continuously without mcreasmg the tag ID precision simply by using abutting regions and maps The 100-bιt region ID allows 2 100 (~10 ,!) or a million trillion trillion) different regions to be uniquely identified 1.2.2 Tag Data Encoding The 120 bits of tag data are redundantly encoded usmg a (15, 5) Reed-Solomon code This yields 360 encoded bits consisting of 6 codewords of 15 4-bit symbols each The (15, 5) code allows up to 5 symbol eπors to be corrected per codeword, l e it is tolerant of a symbol eπor rate ol up to 33% per codeword Each 4-bit symbol is represented m a spatially coherent way m the tag, and the symbols of the six codewords are interleaved spatially withm the tag This ensures that a burst eπor (an error affecting multiple spatially adjacent bits) damages a rrummum number of symbols overall and a minimum number of symbols m any one codeword, thus maximising the likelihood that the burst error can be fullv coπected 1.2.3 Physical Tag Structure The physical representation of the tag. shown m Figure 5 mcludes fixed target structures 15, 16, 17 and vanable data areas 18 The fixed target structures allow a sensing device such as the netpage pen to detect the tag and mfer its three-dimensional onentation relative to the sensor The data areas contam representations of the individual bits of the encoded tag data To achieve proper tag reproduction, the tag is rendered at a resolution of 256x256 dots When pnnted at - 9 - 1600 dots per mch this vields a tag with a diameter of about 4 mm At this resolution the tag is designed to be surrounded by a ' quiet area" of radius 16 dots Smce the quiet area is also contributed bv adjacent tags, it only adds 16 dots to the effective diameter of the tag The tag mcludes six target structures A detection πng 15 allows the sensmg device to initially detect the tag The nng is easy to detect because it is rotationally mvanant and because a simple correction of its aspect ratio removes most of the effects of perspective distortion An onentation axis 16 allows the sensmg device to determine the approximate planar onentation of the tag due to the yaw of the sensor The onentation axis is skewed to yield a u que onentation Four perspective targets 17 allow the sensmg device to infer an accurate two-dimensional perspective transform of the tag and hence an accurate three-dimensional position and onentation of the tag relative to the sensor All target structures are redundantly large to improve their immunity to noise The overall tag shape is circular This supports, amongst other things, optimal tag packing on an rπegular tnangular gnd In combination with the circular detection nng, this makes a circular arrangement of data bits withm the tag optimal To maximise its size, each data bit is represented bv a radial wedge in the form of an area bounded by two radial lmes and two concentnc circular arcs Each wedge has a minimum dimension of 8 dots at 1600 dpi and is designed so that its base (its inner arc), is at least equal to this minimum dimension The height of the wedge m the radial direction is always equal to the minimum dimension Each 4-bit data symbol is represented by an array of 2x2 wedges The 15 4-bit data symbols of each of the six codewords are allocated to the four concentnc symbol rings 18a to 18d m mterleaved fashion Symbols are allocated alternately m cucular progression around the tag The interleaving is designed to maximise the average spatial distance between any two symbols of the same codeword In order to support "single-click" mteraction with a tagged region via a sensmg device, the sensmg device must be able to see at least one entire tag m its field of view no matter where m the region or at what onentation it is positioned The required diameter of the field of view of the sensmg device is therefore a function of the size and spacmg of the tags Assuming a circular tag shape, the rmnimum diameter of the sensor field of view is obtained when the tags are tiled on a equilateral tnangular gnd. as shown m Figure 6 1.2.5 Tag Image Processing and Decoding The tag image processmg and decodmg performed by a sensing device such as the netpage pen is shown in Figure 7 While a captured image is bemg acquired from the image sensor, the dynamic range of the image is determined (at 20) The center of the range is then chosen as the binary threshold for the image 21 The image is then thresholded and segmented mto connected pixel regions (l e shapes 23) (at 22) Shapes which are too small to represent tag target structures are discarded The size and centroid of each shape is also computed Binary shape moments 25 are then computed (at 24) for each shape, and these provide the basis for subsequently locating target structures Central shape moments are by their nature mvanant of position, and can be easily made mvanant of scale, aspect ratio and rotation The πng target structure 15 is the first to be located (at 26) A nng has the advantage of bemg very well behaved when perspective-distorted Matching proceeds by aspect-normalizing and rotation-normalizing each shape s moments Once its second-order moments are normalized the nng is easy to recognize even if the perspective distortion was significant The nng's ongmal aspect and rotation 27 together provide a useful approximation of the perspective transform The axis target structure 16 is the next to be located (at 28) Matching proceeds by applying the nng ' s - 10 - noπnalizations to each shape ' s moments, and rotation-normalizing the resulting moments Once its second-order moments are normalized the axis target is easily recognized Note that one third order moment is required to disambiguate the tw o possible onentations of the axis The shape is deliberately skewed to one side to make this possible Note also that it is only possible to rotation-normalize the axis target after it has had the nng's normalizations applied, smce the perspective distortion can hide the axis target's axis The axis target's ongmal rotation provides a useful approximation of the tag's rotation due to pen yaw 29 The four perspective target structures 17 are the last to be located (at 30) Good estimates of their positions are computed based on their known spatial relationships to the nng and axis targets, the aspect and rotation of the nng, and the rotation of the axis Matching proceeds by applying the nng s normalizations to each shape's moments Once their second-order moments are normalized the circular perspective targets are easy to recognize, and the target closest to each estimated position is taken as a match The ongmal centroids of the four perspective targets are then taken to be the perspective-distorted corners 31 of a square of known size m tag space, and an eight-degree-of-freedom perspective transform 33 is infeπed (at 32) based on solvmg the well-understood equations relating the four tag-space and image- space point pairs The infeπed tag-space to image-space perspective transform is used to project (at 36) each known data bit position m tag space into image space where the real-valued position is used to bilinearlv interpolate (at 36) the four relevant adjacent pixels m the mput image The previously computed image threshold 21 is used to threshold the result to produce the final bit value 37 Once all 360 data bits 37 have been obtained m this way, each of the six 60-bit Reed-Solomon codewords is decoded (at 38) to yield 20 decoded bits 39, or 120 decoded bits m total Note that the codeword symbols are sampled m codeword order, so that codewords are implicitly de-mterleaved dunng the sampling process The πng target 15 is only sought in a subarea of the image whose relationship to the image guarantees that the nng, if found, is part of a complete tag If a complete tag is not found and successfully decoded, then no pen position is recorded for the current frame Given adequate processing power and ideally a non-minimal field of view 193, an alternative strategy involves seeking another tag m the current image The obtained tag data mdicates the identity of the region containing the tag and the position of the tag within the region An accurate position 35 of the pen nib in the region, as well as the overall onentation 35 of the pen, is then inferred (at 34) from the perspective transform 33 observed on the tag and the known spatial relationship between the pen's physical axis and the pen's optical axis 1.2.6 Tag Map Decoding a tag results m a region ID, a tag ID, and a tag-relative pen transform Before the tag ID and the tag-relative pen location can be translated mto an absolute location withm the tagged region, the location of the tag withm the region must be known This is given by a tag map, a function which maps each tag ID in a tagged region to a correspondmg location The tag map class diagram is shown m Figure 22, as part of the netpage pπnter class diagram A tag map reflects the scheme used to tile the surface region with tags, and this can vary accordmg to surface type When multiple tagged regions share the same tiling scheme and the same tag numbering scheme, they can also share the same tag map The tag map for a region must be retnevable via the region ID Thus, given a region ID, a tag ID and a pen transform, the tag map can be retneved. the tag ID can be translated mto an absolute tag location within the region, and the tag-relative pen location can be added to the tag location to yield an absolute pen location withm the region 1.2.7 Tagging Schemes Two distinct surface coding schemes are of mterest, both of which use the tag structure descnbed earlier in - 11 - this section The preferred codmg scheme uses "location-indicating tags as already discussed An alternative coding scheme uses obiect-indicating tags A location-indicating tag contams a tag ID which, when translated through the tag map associated with the tagged region, yields a umque tag location withm the region The tag-relative location of the pen is added to this tag location to yield the location of the pen withm the region This m turn is used to determine the location of the pen relative to a user mterface element m the page descnption associated with the region Not only is the user mterface element itself identified, but a location relative to the user mterface element is identified Location-indicating tags therefore trivially support the capture of an absolute pen path m the zone of a particular user mterface element An object-indicating tag contains a tag ED which directly identifies a user mterface element in the page descnption associated with the region All the tags m the zone of the user mterface element identify the user mterface element, making them all identical and therefore indistinguishable Object-indicating tags do not, therefore, support the capture of an absolute pen path They do, however, support the capture of a relative pen path So long as the position sampling frequency exceeds twice the encountered tag frequency, the displacement from one sampled pen position to the next withm a stroke can be unambiguously determined With either tagging scheme the tags function m cooperation with associated visual elements on the netpage as user interactive elements m that a user can mteract with the pnnted page usmg an appropnate sensmg device in order for tag data to be read by the sensmg device and for an appropnate response to be generated in the netpage system 1.3 DOCUMENT AND PAGE DESCRIPTIONS A prefeπed embodiment of a document and page descnption class diagram is shown m Figures 25 and 26 In the netpage system a document is descnbed at three levels At the most abstract level the document 836 has a hierarchical structure whose terminal elements 839 are associated with content objects 840 such as text objects, text style objects, image objects, etc Once the document is pnnted on a pnnter with a particular page size and according to a particular user's scale factor preference, the document is paginated and otherwise formatted Formatted terminal elements 835 will m some cases be associated with content objects which are different from those associated with then corresponding terminal elements, particularly where the content objects are style-related Each pnnted instance of a document and page is also descπbed separately, to allow mput captured through a particular page instance 830 to be recorded separately from mput captured through other instances ot the same page descnption The presence of the most abstract document descnption on the page server allows a user to request a copy of a document without bemg forced to accept the source document's specific format The user mav be requesting a copy through a pnnter with a different page size, lor example Conversely, the presence of the formatted document descnption on the page server allows the page server to efficiently interpret user actions on a particular pnnted page A formatted document 834 consists of a set of formatted page descnptions 5, each of which consists of a set of formatted terminal elements 835 Each formatted element has a spatial extent or zone 58 on the page This defines the active area of mput elements such as hyperlinks and input fields A document instance 831 corresponds to a formatted document 834 It consists ol a set of page instances 830, each of which corresponds to a page descnption 5 of the formatted document Each page instance 830 descπbes a smgle umque pπnted netpage 1 , and records the page ID 50 ol the netpage A page instance is not part of a document instance if it represents a copy of a page requested in isolation A page instance consists of a set of terminal element instances 832 An element instance only exists if it records instance-specific information Thus, a hyperlink instance exists for a hyperlink element because it records a transaction ID 55 which is specific to the page instance, and a field instance exists lor a field element because it records mput specific to the page instance An element instance does not exist, however, for static elements such as textflows - 12 - A termmal element can be a static element 843, a hyperlink element 844 a field element 845 or a page server command element 846 as shown m Figure 27 A static element 843 can be a style element 847 w th an associated style object 854, a textflow element 848 with an associated styled text object 855, an image element 849 with an associated image element 856, a graphic element 850 with an associated graphic object 857, a video clip element 851 with an associated video clip object 858, an audio clip element 852 with an associated audio clip object 859, or a scnpt element 853 with an associated scnpt object 860, as shown m Figure 28 A page instance has a background field 833 which is used to record any digital ink captured on the page which does not apply to a specific mput element In the prefeπed form of the invention a tag map 811 is associated with each page instance to allow tags on the page to be translated mto locations on the page 1.4 THE NETPAGE NETWORK In a preferred embodiment, a netpage network consists of a distnbuted set of netpage page servers 10, netpage registration servers 11 , netpage ID servers 12, netpage application servers 13, netpage publication servers 14, and netpage pnnters 601 connected via a network 19 such as the Internet, as shown in Figure 3 The netpage registration server 11 is a server which records relationships between users, pens, pπnters, applications and publications, and thereby authorizes vanous network activities It authenticates users and acts as a signing proxy on behalf of authenticated users in application transactions It also provides handwriting recognition services As descnbed above, a netpage page server 10 maintains persistent information about page descnptions and page instances The netpage network mcludes any number of page servers, each handling a subset of page instances Smce a page server also maintains user mput values for each page instance, clients such as netpage pnnters send netpage input duectlv to the appropnate page server The page server interprets any such mput relative to the descnption of the coπesponding page A netpage ID server 12 allocates document IDs 51 on demand and provides load-balancing of page servers via its ID allocation scheme A netpage pnnter uses the Internet Distnbuted Name System (DNS), or similar, to resolve a netpage page ID 50 mto the network address of the netpage page server handling the correspondmg page instance A netpage application server 13 is a server which hosts mteractive netpage applications A netpage publication server 14 is an application server which publishes netpage documents to netpage pnnters They are descnbed m detail m Section 2 Netpage servers can be hosted on a vaπety of network server platforms from manufacturers such as IBM, Hewlett-Packard, and Sun Multiple netpage servers can run concurrently on a smgle host, and a smgle server can be distnbuted over a number of hosts Some or all ol the functionality provided by netpage servers, and in particular the functionality provided by the ED server and the page server, can also be provided directly m a netpage appliance such as a netpage pπnter, in a computer workstation, or on a local network 1.5 THE NETPAGE PRINTER The netpage pnnter 601 is an appliance which is registered with the netpage system and pnnts netpage documents on demand and via subscnption Each pnnter has a umque pnnter ID 62, and is connected to the netpage network via a network such as the Internet, ideally via a broadband connection Apart from identity and secunty settings in non-volatile memory, the netpage pnnter contams no persistent storage As far as a user is concerned, "the network is the computer" Netpages function interactively across space and time with the help of the distnbuted netpage page servers 10, independently of particular netpage pnnters The netpage pnnter receives subscnbed netpage documents from netpage publication servers 14 Each - 13 - document is distributed m two parts the page layouts, and the actual text and image objects which populate the pages Because of personalization, page layouts are typically specific to a particular subscnber and so are pomtcast to the subscnber s pnnter via the appropnate page server Text and image objects, on the other hand, are typically shared with other subscnbers, and so are multicast to all subscnbers' pnnters and the appropnate page servers The netpage publication server optimizes the segmentation of document content mto pomtcasts and multicasts After receivmg the pointcast of a document's page layouts, the pnnter knows which multicasts. if any, to listen to Once the pnnter has received the complete page layouts and objects that define the document to be pnnted, it can pnnt the document The pnnter rastenzes and prints odd and even pages simultaneously on both sides of the sheet It contains duplexed pnnt engine controllers 760 and pnnt engmes utilizing Memjet™ prmtheads 350 for this purpose The pnntmg process consists of two decoupled stages rasterization of page descnptions, and expansion and pnntmg of page images The raster image processor (RE?) consists of one or more standard DSPs 757 nrnnmg m parallel The duplexed pnnt engine controllers consist of custom processors which expand, dither and pnnt page images m real time, synchronized with the operation of the prmtheads m the pnnt engines Pnnters not enabled for IR pnntmg have the option to pnnt tags usmg IR-absorptive black ink. although this restncts tags to otherwise empty areas of the page Although such pages have more limited functionality than IR-pnnted pages, they are still classed as netpages A normal netpage pnnter prints netpages on sheets of paper More specialised netpage pnnters may pnnt onto more specialised surfaces, such as globes Each pnnter supports at least one surface type, and supports at least one tag tiling scheme, and hence tag map, for each surface type The tag map 81 1 which descnbes the tag tiling scheme actually used to pnnt a document becomes associated with that document so that the document's tags can be coπectly interpreted Figure 2 shows the netpage pnnter class diagram, reflecting pπnter-related information mamtamed by a registration server 11 on the netpage network A prefeπed embodiment of the netpage pπnter is descnbed in greater detail m Section 6 below, with reference to Figures 11 to 16 1.5.1 Memjet™ Printheads The netpage system can operate using pnnters made with a wide range of digital pnntmg technologies, mcludmg thermal inkjet, piezoelectric inkjet, laser electrophotographic, and others However, for wide consumer acceptance, it is desuable that a netpage pnnter have the following charactenstics • photographic quality color pnntmg high quality text pnntmg • high reliability • low pnnter cost • low paper cost • simple operation • nearly silent pnntmg • high pnntmg speed • simultaneous double sided pnntmg • compact form factor - 14 - • low power consumption No commercially available printing technology has all of these charactenstics To enable to production of pnnters with these charactenstics. the present applicant has mvented a new pnnt technology, refeπed to as Memjet™ technology Memjet™ is a drop-on-demand inkjet technology that mcorporates pagewidth prmtheads fabncated usmg microelectromechamcal systems (MEMS) technology Figure 17 shows a single pnntmg element 300 of a Memjet™ pnnthead The netpage wallpnnter mcorporates 168960 printing elements 300 to form a 1600 dpi pagewidth duplex pnnter This pnnter simultaneously prints cyan, magenta, yellow, black, and mfrared inks as well as paper conditioner and ink fixative The pnntmg element 300 is approximately 110 microns long by 32 microns wide Aπavs of these pπnting elements are formed on a silicon substrate 301 that incoφorates CMOS logic, data transfer, timing, and dπve circuits (not shown) Major elements of the pπnting element 300 are the nozzle 302, the nozzle nm 303. the nozzle chamber 304, the fluidic seal 305, the ink channel nm 306, the lever arm 307, the active actuator beam pair 308, the passive actuator beam pair 309. the active actuator anchor 310, the passive actuator anchor 31 1 , and the mk inlet 312 The active actuator beam pair 308 is mechanically ]oined to the passive actuator beam pair 309 at the join 319 Both beams pairs are anchored at their respective anchor pomts 310 and 311 The combmation of elements 308, 309, 310, 31 1, and 319 form a cantilevered electrothermal bend actuator 320 Figure 18 shows a small part of an aπay of pnntmg elements 300, mcludmg a cross section 315 of a pπnting element 300 The cross section 315 is shown without ink, to clearly show the ink mlet 312 that passes through the silicon wafer 301 Figures 19(a), 19(b) and 19(c) show the operatmg cycle of a Memjet™ pnntmg element 300 Figure 1 (a) shows the quiescent position of the ink memscus 316 pnor to pnntmg an ink droplet Ink is retained in the nozzle chamber by surface tension at the ink meniscus 316 and at the fluidic seal 305 formed between the nozzle chamber 304 and the ink channel nm 306 While pnntmg, the pnnthead CMOS circuitry distnbutes data from the pnnt engine controller to the correct pπnting element, latches the data, and buffers the data to dnve the electrodes 318 of the active actuator beam pair 308 This causes an electncal current to pass through the beam pair 308 for about one microsecond, resulting m Joule heating The temperature increase resulting from Joule heating causes the beam pair 308 to expand As the passive actuator beam pair 309 is not heated, it does not expand, resulting in a stress difference between the two beam pairs This stress difference is partially resolved by the cantilevered end of the electrothermal bend actuator 320 bending towards the substrate 301 The lever arm 307 transmits this movement to the nozzle chamber 304 The nozzle chamber 304 moves about two microns to the position shown m Figure 19(b) This mcreases the ink pressure, forcmg ink 321 out of the nozzle 302, and causing the ink memscus 316 to bulge The nozzle nm 303 prevents the ink memscus 316 from spreadmg across the surface of the nozzle chamber 304 As the temperature of the beam pairs 308 and 309 equalizes, the actuator 320 returns to its ongmal position This aids in the break-off of the ink droplet 317 from the ink 321 m the nozzle chamber, as shown in Figure 19(c) The nozzle chamber is refilled by the action of the surface tension at the memscus 316 Figure 20 shows a segment of a pnnthead 350 In a netpage pnnter, the length of the pnnthead is the full width of the paper (typically 210 mm) m the direction 351 The segment shown is 0 4 mm long (about 0 2% of a complete pnnthead) When pnntmg, the paper is moved past the fixed pnnthead m the direction 352 The pπnthead has 6 rows of lnterdigitated pnntmg elements 300, pnntmg the six colors or types of ink supplied by the ink inlets 312 To protect the fragile surface of the pnnthead dunng operation, a nozzle guard wafer 330 is attached to the - 15 - pnnthead substrate 301 For each nozzle 302 there is a correspondmg nozzle guard hole 331 through which the ink droplets are fired To prevent the nozzle guard holes 331 from becoming blocked by paper fibers or other debns filtered air is pumped through the air inlets 332 and out of the nozzle guard holes dunng pnntmg To prevent ink 321 from drying, the nozzle guard is sealed while the pnnter is idle 1.6 The Netpage Pen The active sensmg device of the netpage system is typicallv a pen 101 , which, usmg its embedded controller 134, is able to capture and decode IR position tags from a page via an image sensor The image sensor is a solid-state device provided with an appropnate filter to permit sensing at only near-rntrared wavelengths As descnbed m more detail below, the system is able to sense when the nib is m contact with the surface and the pen is able to sense tags at a sufficient rate to capture human handwriting (l e at 200 dpi or greater and 100 Hz or faster) Information captured by the pen is encrypted and wαrelessly transmitted to the pnnter (or base station), the printer or base station interpreting the data with respect to the (known) page structure The preferred embodiment of the netpage pen operates both as a normal markmg ink pen and as a non- mark g stylus The markmg aspect, however is not necessary for usmg the netpage system as a browsmg svstem, such as when it is used as an Internet mterface Each netpage pen is registered with the netpage system and has a umque pen ID 61 Figure 23 shows the netpage pen class diagram, reflecting pen-related information mamtamed by a registration server 11 on the netpage network When either nib is in contact with a netpage, the pen determines its position and onentation relative to the page The nib is attached to a force sensor, and the force on the mb is interpreted relative to a threshold to indicate whether the pen is "'up" or "down" This allows a mteractive element on the page to be 'clicked' by pressmg with the pen mb, m order to request, say, information from a network Furthermore, the force is captured as a continuous value to allow, say, the full dynamics of a signature to be venfied The pen determines the position and onentation of its nib on the netpage by imaging, in the infrared spectrum, an area 193 of the page m the vicinity of the mb It decodes the nearest tag and computes the position of the mb relative to the tag from the observed perspective distortion on the imaged tag and the known geometry of the pen optics Although the position resolution of the tag may be low, because the tag density on the page is inversely proportional to the tag size, the adjusted position resolution is quite high, exceedmg the minimum resolution required for accurate handwriting recognition Pen actions relative to a netpage are captured as a senes of strokes A stroke consists of a sequence of time- stamped pen positions on the page, initiated by a pen-down event and completed by the subsequent pen-up event A stroke is also tagged with the page ID 50 of the netpage whenever the page ID changes, which, under normal circumstances, is at the commencement of the stroke Each netpage pen has a current selection 826 associated with it. allowing the user to perform copy and paste operations etc The selection is timestamped to allow the system to discard it after a defined time penod The current selection descnbes a region of a page instance It consists of the most recent digital ink stroke captured through the pen relative to the background area of the page It is interpreted in an application-specific manner once it is submitted to an application via a selection hyperlink activation Each pen has a current nib 824 This is the mb last notified by the pen to the system In the case of the default netpage pen descnbed above, either the markmg black ink nib or the non-marking stylus mb is cuπent Each pen also has a current mb style 825 This is the mb style last associated with the pen by an application, e g in response to the user selecting a color from a palette The default nib style is the nib style associated with the current mb Strokes captured through a pen are tagged with the current mb style When the strokes are subsequently reproduced, they are - 16 - reproduced m the b style with which they are tagged Whenever the pen is withm range of a pnnter with which it can commumcate, the pen slowly flashes its "online" LED When the pen fails to decode a stroke relative to the page, it momentanly activates its error" LED When the pen succeeds m decoding a stroke relative to the page, it momentanly activates its "ok" LED A sequence of captured strokes is refeπed to as digital ink Digital ink forms the basis for the digital exchange of drawings and handwriting, for online recognition of handwnting, and tor online venfication of signatures The pen is wireless and transmits digital ink to the netpage pnnter via a short-range radio link The transmitted digital ink is encrypted for pnvacy and secunty and packetized for efficient transmission but is alwavs flushed on a pen-up event to ensure timely handling m the pnnter When the pen is out-of-range of a pnnter it buffers digital ink m internal memory, which has a capacity of over ten minutes of continuous handwnting When the pen is once agam withm range of a pπnter, it transfers any buffered digital ink A pen can be registered with any number of pπnters, but because all state data resides m netpages both on paper and on the network, it is largely lmmatenal which pnnter a pen is communicating with at any particular time A preferred embodiment of the pen is descπbed m greater detail m Section 6 below, w th reference to Figures 8 to 10 1.7 NETPAGE INTERACTION The netpage pπnter 601 receives data relating to a stroke from the pen 101 when the pen is used to interact with a netpage 1 The coded data 3 of the tags 4 is read by the pen when it is used to execute a movement, such as a stroke The data allows the identity of the particular page and associated interactive element to be determined and an indication of the relative positioning of the pen relative to the page to be obtained The indicating data is transmitted to the pnnter, where it resolves, via the DNS, the page ID 50 of the stroke mto the network address of the netpage page server 10 which maintains the coπesponding page instance 830 It then transmits the stroke to the page server If the page was recently identified m an earlier stroke, then the printer may already have the address of the relevant page server in its cache Each netpage consists of a compact page layout mamtamed persistently by a netpage page server (see below) The page layout refers to objects such as images, fonts and pieces of text, typically stored elsewhere on the netpage network When the page server receives the stroke from the pen, it retneves the page descnption to which the stroke applies, and determines which element of the page descnption the stroke intersects It is then able to interpret the stroke in the context of the type of the relevant element A "click" is a stroke where the distance and time between the pen down position and the subsequent pen up position are both less than some small maximum An object which is activated bv a click typically requires a click to be activated, and accordingly, a longer stroke is ignored The failure of a pen action, such as a "sloppy" click, to register is mdicated by the lack of response from the pen's "ok" LED There are two kinds of mput elements m a netpage page descnption hyperlinks and form fields Input through a form field can also tngger the activation of an associated hyperlink 1.7.1 Hyperlinks A hyperlink is a means of sending a message to a remote application, and typically elicits a pnnted response m the netpage system A hyperlink element 844 identifies the application 71 which handles activation of the hyperlink, a link ID 54 which identifies the hyperlink to the application, an "alias required" flag which asks the system to mclude the user's application alias ID 65 m the hyperlink activation, and a descnption which is used when the hyperlink is recorded as a - 17 - favonte or appears m the user's historv The hyperlink element class diagram is shown m Figure 29 When a hyperlink is activated, the page server sends a request to an application somewhere on the network The application is identified by an application ID 64, and the application ID is resolved m the normal way via the DNS There are three tvpes of hyperlinks general hyperlinks 863, form hyperlinks 865, and selection hyperlinks 864 as shown m Figure 30 A general hyperlink can implement a request for a linked document, or may simply signal a preference to a server A form hyperlink submits the coπespondmg form to the application A selection hyperlink submits the current selection to the application If the current selection contams a smgle-word piece of text, for example, the application mav return a smgle-page document givmg the word s meanmg withm the context m which it appears, or a translation mto a different language Each hyperlink type is charactenzed by what information is submitted to the application The coπespondmg hyperlink instance 862 records a transaction ID 55 which can be specific to the page instance on which the hyperlink instance appears The transaction ID can identify user-specific data to the application, for example a ' shopping cart" of pending purchases mamtamed by a purchasing application on behalf of the user The system includes the pen s cuπent selection 826 m a selection hyperlmk activation The system includes the content of the associated form instance 868 in a form hyperlink activation, although if the hyperlink has its ' submit delta" attπbute set only mput smce the last form submission is included The svstem mcludes an effective return path in all hyperlink activations A hyperimked group 866 is a group element 838 which has an associated hyperlink, as shown m Figure 31 When mput occurs through any field element m the group, the hyperlink 844 associated with the group is activated A hyperimked group can be used to associate hyperlink behavior with a field such as a checkbox It can also be used, m conjunction with the "submit delta" attribute of a form hyperlink, to provide continuous mput to an application It can therefore be used to support a "blackboard' mteraction model, l e where input is captured and therefore shared as soon as it occurs 1.7.2 Forms A form defines a collection of related mput fields used to capture a related set of inputs through a pnnted netpage A form allows a user to submit one or more parameters to an application software program runnmg on a server A form 867 is a group element 838 m the document hierarchy It ultimatelv contams a set of terminal field elements 839 A form instance 868 represents a pnnted instance of a form It consists of a set of field instances 870 which correspond to the field elements 845 of the form Each field instance has an associated value 871 , whose type depends on the type of the correspondmg field element Each field value records mput through a particular pnnted form instance, l e through one or more pnnted netpages The form class diagram is shown m Figure 32 Each form instance has a status 872 which mdicates whether the form is active, frozen, submitted, void or expued A form is active when first pnnted A form becomes frozen once it is signed A form becomes submitted once one of its submission hyperlinks has been activated, unless the hyperlink has its ' submit delta' attπbute set A form becomes void when the user mvokes a void form, reset form or duplicate form page command A form expires when the time the form has been active exceeds the form s specified lifetime While the form is active, form mput is allowed Input through a form which is not active is mstead captured m the background field 833 of the relevant page instance When the form is active or frozen, form submission is allowed Anv attempt to submit a form when the form is not active or frozen is rejected, and mstead elicits an form status report Each form instance is associated (at 59) with any form instances denved from it, thus providing a version historv This allows all but the latest version of a form m a particular time penod to be excluded from a search All mput is captured as digital ink Digital ink 873 consists ol a set of timestamped stroke groups 874, each - 18 - of which consists of a set of styled strokes 875 Each stroke consists of a set of timestamped pen positions 876, each of which also mcludes pen onentation and mb force The digital ink class diagram is shown in Figure 33 A field element 845 can be a checkbox field 877 a text field 878, a drawing field 879, or a signature field 880 The field element class diagram is shown m Figure 34 Any digital ink captured m a field's zone 58 is assigned to the field A checkbox field has an associated boolean value 881. as shown in Figure 35 Any mark (a tick, a cross, a stroke, a fill zigzag, etc ) captured in a checkbox field's zone causes a true value to be assigned to the field's value A text field has an associated text value 882, as shown m Figure 36 Any digital ink captured m a text field s zone is automatically converted to text via online handwπting recognition, and the text is assigned to the field's value Online handwπting recognition is well-understood (see for example Tappert, C , C Y Suen and T Wakahara, "The State of the Art m On-Line Handwnting Recognition", IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol 12, No 8, August 1990) A signature field has an associated digital signature value 883, as shown in Figure 37 Any digital ink captured in a signature field's zone is automatically venfied with respect to the identity of the owner of the pen, and a digital signature of the content of the form of which the field is part is generated and assigned to the field's value The digital signature is generated using the pen user s pnvate signature key specific to the application which owns the form Online signature venfication is well-understood (see for example Plamondon, R and G Lorette, "Automatic Signature Venfication and Wnter Identification - The State of the Art", Pattern Recognition, Vol 22, No 2, 1989) A field element is hidden if its "hidden" attnbute is set A hidden field element does not have an mput zone on a page and does not accept mput It can have an associated field value which is mcluded in the form data when the form containing the field is submitted "Editing" commands, such as stnke-throughs mdicatmg deletion, can also be recognized in form fields Because the handwnting recognition algonthm works "online" (1 e w th access to the dynamics of the pen movement), rather than "offline" (l e with access only to a bitmap of pen markings), it can recognize run-on discretely- wntten characters with relatively high accuracy, without a wnter-dependent traimng phase A wnter-dependent model of handwriting is automatically generated over time, however, and can be generated up-front if necessary, Digital ink, as already stated, consists of a sequence of strokes Any stroke which starts m a particular element's zone is appended to that element's digital ink stream, ready for interpretation Anv stroke not appended to an object's digital ink stream is appended to the background field's digital ink stream Digital ink captured m the background field is interpreted as a selection gesture Circumscnption of one or more objects is generally interpreted as a selection of the circumscnbed objects, although the actual interpretation is application-specific Table 2 summanses these vanous pen interactions with a netpage Table 2 - Summary of pen interactions with a netpage - 19 - The system maintains a current selection for each pen The selection consists simply of the most recent stroke captured m the background field The selection is cleared after an inactivity timeout to ensure predictable behavior The raw digital ink captured m every field is retained on the netpage page server and is optionallv transmitted with the form data when the form is submitted to the application This allows the application to interrogate the raw digital ink should it suspect the ongmal conversion, such as the conversion of handwritten text This can, for example, involve human intervention at the application level for forms which fail certain application-specific consistency checks As an extension to this, the entire background area of a form can be designated as a drawing field The application can then decide on the basis of the presence of digital mk outside the explicit fields of the form, to route the form to a human operator, on the assumption that the user may have mdicated amendments to the filled-m fields outside of those fields Figure 38 shows a flowchart of the process of handling pen input relative to a netpage The process consists of receivmg (at 884) a stroke from the pen, identifying (at 885) the page instance 830 to which the page ID 50 m the stroke refers, retπeving (at 886) the page descnption 5, identifying (at 887) a formatted element 839 whose zone 58 the stroke mtersects, determining (at 888) whether the formatted element coπesponds to a field element, and if so appendmg (at 892) the received stroke to the digital ink of the field value 871, interpreting (at 893) the accumulated digital ink of the field, and determining (at 894) whether the field is part of a hyperimked group 866 and if so activating (at 895) the associated hyperlink, alternatively deterrmmng (at 889) whether the formatted element coπesponds to a hyperlink element and if so activating (at 895) the corresponding hyperlink, alternatively, m the absence of an mput field or hyperlink, appendmg (at 890) the received stroke to the digital ink of the background field 833, and copying (at 891 ) the received stroke to the current selection 826 of the current pen, as mamtamed by the registration server Figure 38a shows a detailed flowchart of step 893 m the process shown m Figure 38 where the accumulated digital ink of a field is interpreted according to the type of the field The process consists of determining (at 896) whether the field is a checkbox and (at 897) whether the digital ink represents a checkmark, and if so assigning (at 898) a true value to the field value, alternatively determinmg (at 899) whether the field is a text field and if so converting (at 900) the digital ink to computer text, with the help of the appropnate registration server, and assigning (at 901 ) the converted computer text to the field value, alternatively determinmg (at 902) whether the field is a signature field and if so venfying (at 903) the digital ink as the signature of the pen's owner, with the help of the appropnate registration server, creating (at 904) a digital signature of the contents of the coπesponding form, also with the help of the registration server and using the pen owner's pnvate signature kev relating to the corresponding application, and assigning (at 905) the digital signature to the field value 1.7.3 Page Server Commands A page server command is a command which is handled locally by the page server It operates directly on form, page and document instances A page server command 907 can be a void form command 908, a duplicate form command 909, a reset form command 10, a get form status command 911, a duplicate page command 912. a reset page command 913 a get page status command 914, a duplicate document command 915, a reset document command 916, or a get document status command 917, as shown m Figure 39 A void form command voids the coπespondmg form instance A duplicate form command voids the - 20 - coπesponding foπn mstance and then produces an active pnnted copy of the current form mstance with field values preserved The copv contams the same hyperlink transaction IDs as the ongmal, and so is indistinguishable from the ongmal to an application A reset form command voids the correspondmg form mstance and then produces an active pnnted copv of the form mstance with field values discarded A get form status command produces a pnnted report on the status of the coπespondmg foπn mstance, mcludmg who published it, when it was pnnted, for whom it was pnnted, and the form status of the form mstance Smce a form hyperlink mstance contams a transaction ID, the application has to be mvolved m producing a new form mstance A button requesting a new form mstance is therefore typically implemented as a hyperlmk A duplicate page command produces a pnnted copy of the corresponding page mstance with the background field value preserved If the page contams a form or is part of a form, then the duplicate page command is interpreted as a duplicate form command A reset page command produces a pnnted copy of the coπespondmg page mstance with the background field value discarded If the page contams a form or is part of a form, then the reset page command is interpreted as a reset form command A get page status command produces a pπnted report on the status of the coπesponding page instance mcludmg who published it, when it was pnnted, for whom it was pnnted, and the status of any forms it contams or is part of The netpage logo which appears on every netpage is usually associated with a duplicate page element When a page mstance is duplicated with field values preserved, field values are pnnted m then native form, l e a checkmark appears as a standard checkmark graphic, and text appears as typeset text Only drawings and signatures appear m then oπgmal foπn, with a signature accompanied by a standard graphic indicating successful signature venfication A duplicate document command produces a pnnted copy of the coπespondmg document mstance with background field values preserved If the document contams any forms, then the duplicate document command duplicates the forms m the same way a duplicate form command does A reset document command produces a pπnted copy of the coπesponding document mstance with background field values discarded If the document contams any forms, then the reset document command resets the forms m the same way a reset form command does A get document status command produces a pnnted report on the status of the correspondmg document mstance, mcludmg who published it, when it was pnnted, lor whom it was pnnted, and the status of anv forms it contams If the page server command's "on selected" attribute is set, then the command operates on the page identified by the pen's current selection rather than on the page contaiiung the command This allows a menu of page server commands to be pnnted If the target page doesn't contain a page server command element for the designated page server command, then the command is ignored An application can provide application-specific handling by embedding the relevant page server command element m a hyperimked group The page server activates the hyperlink associated with the hyperimked group rather than executing the page server command A page server command element is hidden if its "hidden" attribute is set A hidden command element does not have an mput zone on a page and so cannot be activated directly by a user It can, however, be activated via a page server command embedded in a different page, if that page server command has its on selected" attπbute set 1.8 STANDARD FEATURES OF N ETPAGES In the preferred form, each netpage is pπnted with the netpage logo at the bottom to indicate that it is a netpage and therefore has mteractive properties The logo also acts as a copy button In most cases pressmg the logo produces a copv of the page In the case of a form, the button produces a copy of the entire form And m the case of a secure document, such as a ticket or coupon, the button elicits an explanatory note or advertising page - 21 - The default smgle-page copv function is handled duectly bv the relevant netpage page server Special copv functions are handled by linking the logo button to an application 1.9 USER HELP SYSTEM In a prefeπed embodiment, the netpage pnnter has a smgle button labelled "Help" When pressed it elicits a smgle page of information, mcludmg status of pnnter connection status of pnnter consumables top-level help menu document function menu • top-level netpage network directory The help menu provides a hierarchical manual on how to use the netpage system The document function menu mcludes the following functions pnnt a copy of a document • pnnt a clean copy of a form • pnnt the status of a document A document function is initiated by simply pressmg the button and then touching any page of the document The status of a document mdicates who published it and when, to whom it was delivered, and to whom and when it was subsequently submitted as a form The netpage network directory allows the user to navigate the hierarchy of publications and services on the network As an alternative, the user can call the netpage network "900" number "yellow pages" and speak to a human operator The operator can locate the desued document and route it to the user's pnnter Depending on the document type, the publisher or the user pays the small "yellow pages' service fee The help page is obviously unavailable if the pnnter is unable to pnnt In this case the "error" light is lit and the user can request remote diagnosis over the network 2 PERSONALIZED PUBLICATION MODEL In the following descnption, news is used as a canonical publication example to illustrate personalization mechanisms in the netpage svstem Although news is often used in the limited sense of newspaper and newsmagazme news, the mtended scope in the present context is wider In the netpage system, the editonal content and the advertising content of a news publication are personalized using different mechamsms The editonal content is personalized accordmg to the reader's explicitly stated and implicitly captured interest profile The advertising content is personalized accordmg to the reader's locality and demographic 2.1 EDITORIAL PERSONALIZATION A subscnber can draw on two lands of news sources those that deliver news publications, and those that deliver news streams While news publications are aggregated and edited by the publisher, news streams are aggregated either by a news publisher or by a specialized news aggregator News publications typically coπespond to traditional newspapers and newsmagazmes, while news streams can be many and vaned a "raw" news feed from a news service, a cartoon stnp, a freelance writer's column, a friend's bulletin board, or the reader's own e-mail The netpage publication server supports the publication of edited news publications as well as the aggregation of multiple news streams By handling the aggregation and hence the formatting of news streams selected directly by the reader, the server is able to place advertising on pages over which it otherwise has no editonal control The subscnber builds a dailv newspaper bv selecting one or more contnbuting news publications, and - 22 - creating a personalized version of each The resulting daily editions are pnnted and bound together mto a smgle newspaper The vanous members of a household typically express their different mterests and tastes by selecting different daily publications and then customizing them For each publication, the reader optionally selects specific sections Some sections appear daily, while others appear weekly The daily sections available from The New York Times online, for example, mclude "Page One Plus" "National", "International", "Opinion", "Business", "Arts/Living" ' Technology' , and "Sports" The set of available sections is specific to a publication, as is the default subset The reader can extend the daily newspaper by creating custom sections, each one drawing on any number ol news streams Custom sections might be created for e-mail and friends announcements ("Personal"), or for momtonng news feeds for specific topics ("Alerts' or "Clippings") For each section, the reader optionally specifies its size either qualitatively (e g short, medium, or long), or numencally (l e as a limit on its number of pages), and the desired proportion of advertising, either qualitatively (e g high, normal, low, none), or numencally (l e as a percentage) The reader also optionally expresses a preference for a large number of shorter articles or a small number of longer articles Each article is ideally wntten (or edited) in both short and long forms to support this preference An article may also be wπtten (or edited) m different versions to match the expected sophistication of the reader, for example to provide children's and adults' versions The appropnate version is selected accordmg to the reader's age The reader can specify a "reading age" which takes precedence over their biological age The articles which make up each section are selected and pnontized by the editors, and each is assigned a useful lifetime By default they are delivered to all relevant subscnbers, in pnonty order, subject to space constraints in the subscπbers' editions In sections where it is appropnate, the reader may optionally enable collaborative filtenng This is then applied to articles which have a sufficiently long lifetime Each article which qualifies lor collaborative filtenng is pnnted with rating buttons at the end of the article The buttons can provide an easy choice (e g "liked ' and "disliked'), making it more likely that readers will bother to rate the article Articles with high pnonties and short lifetimes are therefore effectivelv considered essential reading by the editors and are delivered to most relevant subscnbers The reader optionally specifies a serendipity factor, either qualitatively (e g do or don't surpnse me), or numencally A high serendipity factor lowers the threshold used for matching dunng collaborative filtenng A high factor makes it more likely that the correspondmg section will be filled to the reader's specified capacity A different serendipity factor can be specified for different days of the week The reader also optionally specifies topics of particular interest withm a section, and this modifies the pnonties assigned by the editors The speed of the reader's Internet connection affects the quality at which images can be delivered The reader optionally specifies a preference for fewer images or smaller images or both If the number or size of images is not reduced, then images may be delivered at lower quality (l e at lower resolution or with greater compression) At a global level, the reader specifies how quantities, dates, times and monetary values are localized This mvolves specifying whether units are impenal or metnc, a local timezone and time format, and a local currency, and whether the localization consist of in situ translation or annotation These preferences are denved from the reader s locality by default To reduce readmg difficulties caused by poor eyesight, the reader optionally specifies a global preference for a larger presentation Both text and images are scaled accordingly and less information is accommodated on each - 23 - page The language m which a news publication is published, and its coπespondmg text encoding, is a property of the publication and not a preference expressed by the user However, the netpage svstem can be configured to provide automatic translation services m vanous guises 2.2 ADVERTISING LOCALIZATION AND TARGETING The personalization of the editonal content directly affects the advertising content, because advertising is typically placed to exploit the editonal context Travel ads, for example, are more likelv to appear m a travel section than elsewhere The value of the editonal content to an advertiser (and therefore to the publisher) lies m its ability to attract large numbers of readers with the πght demographics Effective advertising is placed on the basis of locality and demographics Locality determines proximity to particular services, retailers etc , and particular interests and concerns associated with the local community and environment Demographics determine general interests and preoccupations as well as likely spendmg patterns A news publisher's most profitable product is advertising "space' , a multi-dimensional entity determined by the publication's geographic coverage, the size of its readership, its readership demographics, and the page area available for advertising In the netpage svstem, the netpage publication server computes the approximate multi-dimensional size of a publication's saleable advertising space on a per-section basis, taking mto account the publication's geographic coverage, the section's readership, the size of each reader's section edition, each reader's advertising proportion, and each reader's demographic In companson with other media, the netpage system allows the advertising space to be defined m greater detail, and allows smaller pieces of it to be sold separately It therefore allows it to be sold at closer to its true value For example, the same advertising "slot" can be sold in varying proportions to several advertisers, with individual readers' pages randomly receivmg the advertisement of one advertiser or another, overall preserving the proportion of space sold to each advertiser The netpage system allows advertising to be linked directly to detailed product information and online purchasing It therefore raises the intrinsic value of the advertising space Because personalization and localization are handled automatically' bv netpage publication servers, an advertising aggregator can provide arbitraπly broad coverage of both geography and demographics The subsequent disaggregation is efficient because it is automatic This makes it more cost-effective for publishers to deal with advertising aggregators than to duectly capture advertising Even though the advertising aggregator is taking a proportion of advertising revenue, publishers may find the change profit-neutral because of the greater efficiency of aggregation The advertising aggregator acts as an intermediary between advertisers and publishers, and may place the same advertisement in multiple publications It is worth noting that ad placement m a netpage publication can be more complex than ad placement in the publication's traditional counterpart, because the publication's advertising space is more complex While ignoring the full complexities of negotiations between advertisers, advertising aggregators and publishers, the preferred form of the netpage svstem provides some automated support for these negotiations, mcludmg support for automated auctions of advertising space Automation is particularlv desirable for the placement of advertisements which generate small amounts of income, such as small or highly localized advertisements Once placement has been negotiated, the aggregator captures and edits the advertisement and records it on a netpage ad server Coπespondingly, the publisher records the ad placement on the relevant netpage publication server When the netpage publication server lavs out each user's personalized publication, it picks the relevant advertisements - 24 - from the netpage ad server Accordingly a user may be provided with a netpages which mav more generally be referred to as a pπnted document with user mteractive elements, formatted in accordance with their own preferences, with additional content targeted specifically to demographics of the user The mteractive element(s) relating to the targeted content allow the user to request further information relating to that content The targeted content may relate to advertismg matenal and the further mformation may be provided m the form of an advertismg brochure The manner m which the mteractive element(s) are pπnted in the document and with which the sensmg device is used to mteract with the element(s), to mdicate a request for further information, are as descnbed above 2.3 USER PROFILES 2.3.1 Information Filtering The personalization of news and other publications relies on an assortment of user-specific profile information, mcludmg publication customizations collaborative filtenng vectors • contact details presentation preferences The customization of a publication is typically publication-specific, and so the customization mformation is mamtamed by the relevant netpage publication server A collaborative filtenng vector consists of the user s ratings of a number of news items It is used to correlate different users' mterests for the purposes of making recommendations Although there are benefits to maintaining a single collaborative filtenng vector independently of any particular publication, there are two reasons why it is more practical to maintain a separate vector for each publication there is likely to be more overlap between the vectors of subscπbers to the same publication than between those of subscnbers to different publications, and a publication is likely to want to present its users collaborative filtenng vectors as part of the value of its brand, not to be found elsewhere Collaborative filtenng vectors are therefore also mamtamed by the relevant netpage publication server Contact details, mcludmg name, street address, ZIP Code, state, country, telephone numbers, are global by nature, and are mamtamed by a netpage registration server Presentation preferences, mcludmg those for quantities dates and times, are likewise global and mamtamed in the same way The localization of advertising relies on the locality mdicated m the user s contact details, while the targeting of advertismg relies on personal information such as date of birth, gender, maπtal status, mcome, profession, education or qualitative deπvatives such as age range and mcome range For those users who choose to reveal personal information for advertismg purposes, the information is mamtamed by the relevant netpage registration server In the absence of such information advertismg can be targeted on the basis of the demographic associated with the user s ZIP or ZIP+4 Code Each user pen, pπnter, application provider and application is assigned its own unique identifier, and the netpage registration server maintains the relationships between them, as shown in Figures 21, 22, 23 and 24 For registration purposes, a publisher is a special kmd of application provider, and a publication is a special land of application Each user 800 may be authorized to use any number of pnnters 802 and each pnnter may allow any number of users to use it Each user has a smgle default pπnter (at 66), to which peπodical publications are delivered by default whilst pages pnnted on demand are delivered to the pnnter through which the user is interacting The server keeps track - 25 - of which publishers a user has authonzed to pnnt to the user's default pnnter A publisher does not record the ID of anv particular pnnter. but mstead resolves the ID when it is required When a user subscnbes 808 to a publication 807, the publisher 806 (l e application provider 803) is authoπzed to pπnt to a specified pπnter or the user's default pnnter This authorization can be revoked at any tune by the user Each user may have several pens 801. but a pen is specific to a single user If a user is authorized to use a particular pnnter, then that pπnter recognizes any of the user ' s pens The pen ID is used to locate the correspondmg user profile mamtamed by a particular netpage registration server, via the DNS m the usual way A Web terminal 809 can be authorized to pnnt on a particular netpage pnnter. allowing Web pages and netpage documents encountered dunng Web browsmg to be conveniently pnnted on the nearest netpage pnnter The netpage system can collect, on behalf of a pπnter provider, fees and commissions on mcome earned through publications pπnted on the provider's pnnters Such mcome can mclude advertising fees, click-through fees, e- commerce commissions, and transaction fees If the pnnter is owned by the user, then the user is the pnnter provider Each user also has a netpage account 820 which is used to accumulate micro-debits and credits (such as those descnbed m the precedmg paragraph), contact details 815. mcludmg name, address and telephone numbers, global preferences 816, mcludmg pnvacy, delivery and localization settings, anv number of biometnc records 817. containing the user ' s encoded signature 818, fingerprint 819 etc, a handwriting model 819 automatically mamtamed by the system, and SET payment card accounts 821 with which e-commerce payments can be made 2.3.2 Favorites List A netpage user can maintain a list 922 of "favontes" - links to useful documents etc on the netpage network The list is mamtamed by the system on the user's behalf It is organized as a hierarchy of folders 924, a preferrred embodiment of which is shown m the class diagram in Figure 41 2.3.3 History List The system maintains a history list 929 on each user's behalf, containing links to documents etc accessed by the user through the netpage system It is organized as a date-ordered list, a preferred embodiment of which is shown m the class diagram m Figure 42 2.4 INTELLIGENT PAGE LAYOUT The netpage publication server automatically lavs out the pages of each user's personalized publication on a section-bv-section basis Smce most advertisements are m the form of pre-formatted rectangles, they are placed on the page before the editonal content The advertismg ratio for a section can be achieved with wildly varying advertismg ratios on individual pages withm the section, and the ad layout algoπthm exploits this The algonthm is configured to attempt to co-locate closely tied editonal and advertismg content, such as placing ads tor roofing matenal specifically withm the publication because of a special feature on do-it-vourself roofing repairs The editonal content selected for the user, mcludmg text and associated images and graphics, is then laid out accordmg to vanous aesthetic rules The entire process, mcludmg the selection of ads and the selection of editonal content, must be iterated once the layout has converged, to attempt to more closelv achieve the user's stated section size preference The section size preference can, however, be matched on average over time, allowing significant day-to-day vanations 2.5 DOCUMENT FORMAT Once the document is laid out, it is encoded for efficient distribution and persistent storage on the netpage network - 26 - The primary efficiency mechanism is the separation of information specific to a smgle user's edition and information shared between multiple users' editions The specific mformation consists of the page layout The shared information consists of the objects to which the page layout refers, mcludmg images, graphics, and pieces of text A text object contains fully-formatted text represented m the Extensible Markup Language (XML) using the Extensible Stylesheet Language (XSL) XSL provides precise control over text formatting mdependently of the region mto which the text is bemg set, which m this case is bemg provided bv the layout The text object contams embedded language codes to enable automatic translation, and embedded hyphenation hints to aid with paragraph formatting An image object encodes an image m the JPEG 2000 wavelet-based compressed image format A graphic object encodes a 2D graphic m Scalable Vector Graphics (SVG) format The layout itself consists of a senes of placed image and graphic objects, linked textflow objects through which text objects flow, hyperlinks and input fields as descnbed above and watermark regions These layout objects are summarized in Table 3 The layout uses a compact format suitable for efficient distribution and storage Table 3 - netpage layout objects 2.6 DOCUMENT DISTRIBUTION As descnbed above, for purposes of efficient distnbution and persistent storage on the netpage network, a user-specific page layout is separated from the shared objects to which it refers When a subscπbed publication is ready to be distnbuted, the netpage publication server allocates, with the help of the netpage ID server 12, a umque ID lor each page, page instance, document and document mstance The server computes a set of optimized subsets of the shared content and creates a multicast channel lor each subset, and then tags each user-specific layout with the names of the multicast channels which will carry the shared content used by that layout The server then pointcasts each user's layouts to that user's pnnter via the appropnate page server, and when the pointcasting is complete, multicasts the shared content on the specified channels After receiving its pomtcast, each page server and pnnter subscnbes to the multicast channels specified m the page layouts Dunng the multicasts, each page server and pnnter extracts from the multicast streams those objects referred to by its page layouts The page servers persistently archive the received page layouts and shared content - 27 - Once a pnnter has received all the objects to which its page lavouts refer the pnnter re-creates the fully - populated layout and then rastenzes and pπnts it Under normal circumstances, the pnnter prints pages faster than they can be delivered Assuming a quarter of each page is covered with images, the average page has a size of less than 400KB The pnnter can therefore hold m excess of 100 such pages m its internal 64MB memory, allowing tor temporary buffers etc The pπnter prints at a rate of one page per second This is equivalent to 400KB or about 3Mbit of page data per second, which is similar to the highest expected rate of page data delivery over a broadband network Even under abnormal cucumstances, such as when the pπnter runs out of paper, it is likely that the user will be able to replemsh the paper supply before the prmter s 100-page internal storage capacity is exhausted However, if the pnnter s internal memory does fill up then the pπnter will be unable to make use of a multicast when it first occurs The netpage publication server therelore allows pnnters to submit requests for re- multicasts When a cntical number of requests is received or a timeout occurs the server re-multicasts the corresponding shared objects Once a document is pπnted, a pnnter can produce an exact duplicate at any time by retnevmg its page layouts and contents from the relevant page server 2.7 ON-DEMAND DOCUMENTS When a netpage document is requested on demand, it can be personalized and delivered m much the same way as a penodical However, since there is no shared content, delivery is made duectly to the requesting prmter without the use of multicast When a non-netpage document is requested on demand, it is not personalized, and it is delivered via a designated netpage formatting server which reformats it as a netpage document A netpage formatting server is a special mstance of a netpage publication server The netpage formatting server has knowledge of vanous Internet document formats, mcludmg Adobe's Portable Document Format (PDF), and Hypertext Markup Language (HTML) In the case of HTML it can make use of the higher resolution of the pnnted page to present Web pages in a multi-column format, with a table of contents It can automatically mclude all Web pages directly linked to the requested page The user can tune this behavior via a preference The netpage formatting server makes standard netpage behavior, including interactivity and persistence, available on any Internet document, no matter what its ongin and format It hides knowledge of different document formats from both the netpage pπnter and the netpage page server, and hides knowledge of the netpage system from Web servers 2.8 BOOKS As may be appreciated from the above, the netpage svstem also allows for delivery of books The information is formatted usmg an appropnate server and the book is then pπnted at a netpage pπnter with appropnate coded data tags to allow for user mteraction with a sensmg device, such as the netpage pen, m a manner descnbed above, m order to request further mformation relating to the contents of the book The further information is preferably pπnted on demand at the pnnter following a request for same Having books available for pnntmg on the netpage system also means that users can obtain the latest bestsellers or rare ' out-of-pnnt" (a soon-to-be-obsoleted teπn) editions on demand, pnnted in column format with a text size chosen by the user A typical 300-page paperback fits on as little as 40 sheets of Letter paper Slip-on covers are available for robust handling Titles which have outlived their copynght penod can be available for free Other titles can be heavily discounted lor netpage delivery, since publishers avoid the costs of pnntmg inventor, storage and delivery - 28 - Colourful children s books reproduce immaculately When they've been lov ed to death they can be pnnted agam, and agam Children s colonng-m books and puzzles are available just when they re needed on a ramy day 3 SECURITY 3.1 CRYPTOGRAPHY Cryptography is used to protect sensitive information, both in storage and m transit, and to authenticate parties to a transaction There are two classes of cryptographv m widespread use secret-key cryptographv and public-key cryptography The netpage network uses both classes of cryptography Secret-key cryptography, also referred to as symmetnc cryptography, uses the same key to encrypt and decrypt a message Two parties wishing to exchange messages must first arrange to securely exchange the secret key Pubhc-kev cryptographv, also referred to as asvmmetnc cryptography, uses two encryption keys The two keys are mathematically related m such a way that any message encrypted using one key can only be decrypted usmg the other kev One of these keys is then published, while the other is kept pnvate The public key is used to encrypt any message intended for the holder of the pnvate key Once encrypted usmg the public key, a message can only be decrypted using the pnvate key Thus two parties can securely exchange messages without first having to exchange a secret key To ensure that the pnvate key is secure, it is normal for the holder of the pnvate key to generate the key pair Public-key cryptography can be used to create a digital signature The holder of the pnvate key can create a known hash of a message and then encrypt the hash usmg the pnvate key Anyone can then venfy that the encrypted hash constitutes the "signature" of the holder of the pπvate key with respect to that particular message by decrypting the encrypted hash usmg the public key and venfying the hash against the message If the signature is appended to the message, then the recipient of the message can veπfy both that the message is genmne and that it has not been altered in transit To make public-key cryptographv work, there has to be a way to distnbute public keys which prevents impersonation This is normally done usmg certificates and certificate authonties A certificate authonty is a trusted third party which authenticates the connection between a public key and someone's identity The certificate authonty venfies the person's identity by examining identity documents, and then creates and signs a digital certificate containing the person s identity details and public key Anyone who trusts the certificate authonty can use the public key m the certificate with a high degree of certainty that it is genmne They just have to ventv that the certificate has mdeed been signed by the certificate authonty, whose public key is well-known In most transaction envuonments, public-key cryptography is only used to create digital signatures and to securely exchange secret session kevs Secret-key cryptography is used for all other purposes In the following discussion, when reference is made to the secure transmission of mformation between a netpage pπnter and a server what actually happens is that the pnnter obtains the server s certificate, authenticates it with reference to the certificate authonty, uses the public key-exchange key m the certificate to exchange a secret session key with the server, and then uses the secret session key to encrypt the message data A session key, by definition can have an arbitranly short lifetime 3.2 NETPAGE PRINTER SECURITY Each netpage pnnter is assigned a pair of umque identifiers at time of manufacture which are stored m read-only memory in the pπnter and m the netpage registration server database The first ID 62 is public and uniquely identifies the pnnter on the netpage network The second ID is secret and is used when the pnnter is first registered on the network When the pπnter connects to the netpage network for the first time after installation, it creates a signature - 29 - public/pnvate key pair It transmits the secret ID and the public key securely to the netpage registration server The server compares the secret ID against the pnnter s secret ID recorded m its database, and accepts the registration if the IDs match It then creates and signs a certificate containing the pnnter s public ID and public signature key , and stores the certificate m the registration database The netpage registration server acts as a certificate authonty for netpage pnnters, smce it has access to secret information allowing it to venfy pnnter identity When a user subscnbes to a publication, a record is created m the netpage registration server database authonzmg the publisher to pnnt the publication to the user's default pπnter or a specified pπnter Every document sent to a pnnter via a page server is addressed to a particular user and is signed by the publisher usmg the publisher s pπvate signature key The page server venfies, via the registration database, that the publisher is authonzed to deliver the publication to the specified user The page server venfies the signature usmg the publisher s public key, obtained from the publisher's certificate stored m the registration database The netpage registration server accepts requests to add pnntmg authorizations to the database, so long as those requests are initiated via a pen registered to the pnnter 3.3 NETPAGE PEN SECURITY Each netpage pen is assigned a umque identifier at time of manufacture which is stored m read-only memory m the pen and in the netpage registration server database The pen ID 61 uniquely identifies the pen on the netpage network A netpage pen can "know' a number of netpage pnnters, and a pπnter can ' know" a number of pens A pen communicates with a pnnter via a radio frequency signal whenever it is withm range of the pnnter Once a pen and pnnter are registered, they regularly exchange session keys Whenever the pen transmits digital ink to the pnnter, the digital ink is always encrypted usmg the appropnate session key Digital ink is never transmitted in the clear A pen stores a session key for every pnnter it knows, mdexed by pnnter ID, and a pnnter stores a session key for every pen it knows, mdexed bv pen ID Both have a large but finite storage capacity for session keys, and will forget a session key on a least-recentlv-used basis if necessary When a pen comes withm range of a pπnter, the pen and pnnter discover whether they know each other If they don't know each other, then the pnnter determines whether it is supposed to know the pen This might be, for example, because the pen belongs to a user who is registered to use the pnnter If the pnnter is meant to know the pen but doesn't, then it initiates the automatic pen registration procedure If the pπnter isn't meant to know the pen, then it agrees with the pen to ignore it until the pen is placed m a charging cup, at which time it initiates the registration procedure In addition to its public ID, the pen contains a secret kev-exchange key The key-exchange key is also recorded in the netpage registration server database at time of manufacture Dunng registration, the pen transmits its pen ID to the pπnter, and the pπnter transmits the pen ID to the netpage registration server The server generates a session key for the pπnter and pen to use, and securely transmits the session key to the pnnter It also transmits a copy of the session key encrypted with the pen's key-exchange key The pnnter stores the session key internally, indexed by the pen ID, and transmits the encrypted session kev to the pen The pen stores the session key internally, mdexed by the pnnter ID Although a lake pen can impersonate a pen in the pen registration protocol, only a real pen can decrypt the session key transmitted by the pπnter When a previously unregistered pen is first registered, it is of limited use until it is linked to a user A registered but "un-owned' pen is only allowed to be used to request and fill m netpage user and pen registration forms - 30 - to register a new user to which the new pen is automatically linked, or to add a new pen to an existing user The pen uses secret-key rather than public-key encryption because of hardware performance constraints m the pen 3.4 SECURE DOCUMENTS The netpage svstem supports the delivery of secure documents such as tickets and coupons The netpage pπnter mcludes a facility to pnnt watermarks, but will only do so on request from publishers who are suitablv authonzed The publisher mdicates its authonty to pnnt watermarks m its certificate, which the pnnter is able to authenticate The "watermark " pnntmg process uses an alternative dither matrix m specified '~watermark" regions of the page Back-to-back pages contain mirror-image watermark regions which coincide when pπnted The dither matnces used in odd and even pages ' watermark regions are designed to produce an interference effect when the regions are viewed together, achieved by looking through the pπnted sheet The effect is similar to a watermark in that it is not visible when looking at onlv one side of the page, and is lost when the page is copied by normal means Pages of secure documents cannot be copied using the built-m netpage copy mechanism descπbed m Section 1 9 above This extends to copying netpages on netpage-aware photocopiers Secure documents are typically generated as part of e-commerce transactions They can therefore include the user's photograph which was captured when the user registered biometπc information with the netpage registration server, as descnbed m Section 2 When presented with a secure netpage document, the recipient can venfy its authenticity by requesting its status m the usual way The unique ID of a secure document is only valid for the lifetime of the document, and secure document IDs are allocated non-contiguously to prevent then prediction by opportunistic forgers A secure document venfication pen can be developed with built-in feedback on venfication failure, to support easy pomt-of-presentation document venfication Clearly neither the watermark nor the user's photograph are secure m a cryptographic sense They simply provide a significant obstacle to casual forgery Online document venfication, particularly usmg a venfication pen. provides an added level of secunty where it is needed, but is still not entirely immune to forgenes 3.5 NON-REPUDIATION In the netpage system, forms submitted by users are delivered rehablv to forms handlers and are persistently archived on netpage page servers. It is therefore impossible for recipients to repudiate delivery E-commerce payments made through the system, as descnbed in Section 4, are also impossible for the payee to repudiate 4 ELECTRONIC COMMERCE MODEL 4.1 SECURE ELECTRONIC TRANSACTION (SET) The netpage system uses the Secure Electronic Transaction (SET) system as one of its payment systems SET, havmg been developed by MasterCard and Visa, is organized around payment cards, and this is reflected m the terminology However, much of the system is independent of the type of accounts bemg used In SET, cardholders and merchants register with a certificate authonty and are issued with certificates containing their public signature keys The certificate authonty venfies a cardholder's registration details with the card issuer as appropnate, and venfies a merchant's registration details with the acquirer as appropnate Cardholders and merchants store their respective pnvate signature keys securely on their computers Dunng the payment process, these certificates are used to mutually authenticate a merchant and cardholder, and to authenticate them both to the payment - 31 - gatewav SET has not et been adopted widely partly because cardholder maintenance of keys and certificates is considered burdensome Interim solutions which maintain cardholder keys and certificates on a server and give the cardholder access via a password have met with some success 4.2 SET PAYMENTS In the netpage system the netpage registration server acts as a proxy for the netpage user (l e the cardholder) m SET payment transactions The netpage svstem uses biometncs to authenticate the user and authorize SET payments Because the system is pen-based, the biometπc used is the user s on-line signature, consisting of time-varying pen position and pressure A fmgerpnnt biometnc can also be used by designmg a fmgerpnnt sensor mto the pen, although at a higher cost The type of biometnc used only affects the capture of the biometnc, not the authorization aspects of the system The first step to bemg able to make SET payments is to register the user s biometnc w th the netpage registration server This is done in a controlled envuonment, for example a bank where the biometnc can be captured at the same time as the user's identity is venfied The biometπc is captured and stored m the registration database linked to the user s record The user's photograph is also optionally captured and linked to the record The SET cardholder registration process is completed, and the resulting pnvate signature key and certificate are stored m the database The user's payment card information is also stored, givmg the netpage registration server enough information to act as the user's proxy m any SET payment transaction When the user eventually supplies the biometnc to complete a payment, for example by signing a netpage order form, the pnnter securely transmits the order information, the pen ID and the biometnc data to the netpage registration server The server veπfies the biometπc w th respect to the user identified by the pen ID, and from then on acts as the user's proxy m completing the SET payment transaction 4.3 MICRO-PAYMENTS The netpage svstem mcludes a mechanism for micro-payments to allow the user to be conveniently charged for printing low-cost documents on demand and for copying copynght documents, and possibly also to allow the user to be reimbursed for expenses incurred m pπnting advertismg matenal The latter depends on the level of subsidy alreadv provided to the user When the user registers for e-commerce a network account is established which aggregates micro- payments The user receives a statement on a regular basis, and can settle anv outstanding debit balance usmg the standard payment mechanism The network account can be extended to aggregate subscnption fees for penodicals, which would also otherwise be presented to the user m the form of individual statements 4.4 TRANSACTIONS When a user requests a netpage m a particular application context, the application is able to embed a user- specific transaction ID 55 m the page Subsequent mput through the page is tagged with the transaction ID, and the application is thereby able to establish an appropnate context for the user's input When input occurs through a page which is not user-specific, however the application must use the user's umque identity to establish a context A typical example mvolves adding items from a pre-pπnted catalog page to the user's virtual "shopping cart" To protect the user's pnvacy, however, the umque user ID 60 known to the netpage system is not divulged to applications This is to prevent different application providers from easily coπelating mdependently accumulated behavioral data The netpage registration server mstead maintains an anonymous relationship between a user and an - 32 - application via a umque alias ID 65. as shown in Figure 24 Whenever the user activates a hyperlink tagged with the 'registered" attπbute, the netpage page server asks the netpage registration server to translate the associated application ID 64, together with the pen ID 61 , mto an alias ID 65 The alias ID is then submitted to the hyperlink's application The application maintains state information mdexed by alias ED, and is able to retneve user-specific state information without knowledge of the global identity of the user The system also maintains an mdependent certificate and pπvate signature key for each of a user's applications, to allow it to sign application transactions on behalf of the user usmg only application-specific mformation To assist the system m routing product bar code (UPC) "hyperlink" activations, the system records a favonte application on behalf of the user for anv number of product types Each application is associated with an application provider, and the system maintains an account on behalf of each application provider, to allow it to credit and debit the provider for click-through tees etc An application provider can be a publisher of penodical subscnbed content The svstem records the user s willingness to receive the subscπbed publication, as well as the expected frequency of publication 4.5 RESOURCE DESCRIPTIONS AND COPYRIGHT A prefeπed embodiment of a resource descnption class diagram is shown m Figure 40 Each document and content object may be descπbed by one or more resource descnptions 842 Resource descnptions use the Dublin Core metadata element set, which is designed to facilitate discovery of electronic resources Dublm Core metadata conforms to the World Wide Web Consortium (W3C) Resource Descnption Framework (RDF) A resource descnption may identify nghts holders 920 The netpage system automatically transfers copynght fees from users to nghts holders when users pπnt copynght content 5 COMMUNICATIONS PROTOCOLS A communications protocol defines an ordered exchange of messages bet een entities In the netpage system, entities such as pens, pnnters and servers utilise a set of defined protocols to cooperatively handle user mteraction with the netpage system Each protocol is illustrated by way of a sequence diagram in which the honzontal dimension is used to represent message flow and the vertical dimension is used to represent tune Each entity is represented by a rectangle containing the name of the entity and a vertical column representing the lifeline of the entitv Dunng the time an entity exists, the lifeline is shown as a dashed lme Dunng the tune an entity is active, the lifeline is shown as a double lme Because the protocols considered here do not create or destroy entities, lifelines are generally cut short as soon as an entity ceases to participate m a protocol 5.1 SUBSCRIPTION DELIVERY PROTOCOL A prefeπed embodiment of a subscnption delivery protocol is shown in Figure 43 A large number of users may subscnbe to a penodical publication Each user's edition may be laid out differently, but many users' editions will share common content such as text obiects and image objects The subscnption delivery protocol therefore delivers document structures to individual pπnters via pomtcast. but delivers shared content objects via multicast The application (I e publisher) first obtains a document ID 51 for each document from an ID server 12 It then sends each document structure, mcludmg its document ID and page descnptions, to the page server 10 responsible for the document's newly allocated ID It mcludes its own application ID 64, the subscnber's alias ID 65. and the relevant set of multicast channel names It signs the message usmg its pnvate signature key The page server uses the application ED and alias ID to obtain from the registration server the correspondmg user ID 60, the user s selected pnnter ED 62 (which mav be explicitly selected for the application, or may be the user s - 33 - default prmter). and the application s certificate The application s certificate allows the page server to venfy the message signature The page server s request to the registration server fails if the application ED and alias ED don t together identify a subscnption 808 The page server then allocates document and page mstance IDs and forwards the page descπptions, mcludmg page IDs 50, to the pπnter It mcludes the relevant set of multicast channel names for the prmter to listen to It then returns the newly allocated page IDs to the application for future reference Once the application has distnbuted all of the document structures to the subscnbers selected pnnters via the relevant page servers, it multicasts the vanous subsets of the shared objects on the previouslv selected multicast channels Both page servers and pnnters momtor the appropnate multicast channels and receive then required content objects They are then able to populate the previously pomtcast document structures This allows the page servers to add complete documents to their databases, and it allows the pnnters to pnnt the documents 5.2 HYPERLINK ACTIVATION PROTOCOL A prefeπed embodiment of a hyperlmk activation protocol is shown in Figure 45 When a user clicks on a netpage with a netpage pen, the pen communicates the click to the nearest netpage pπnter 601 The click identifies the page and a location on the page The pnnter already knows the ED 61 of the pen from the pen connection protocol The pnnter determines, via the DNS, the network address of the page server 10a handling the particular page ED 50 The address may already be m its cache if the user has recently interacted with the same page The prmter then forwards the pen ED, its own pnnter ED 62, the page ID and click location to the page server The page server loads the page descnption 5 identified by the page ED and deteπrunes which mput element's zone 58, if any, the click lies m Assuming the relevant mput element is a hyperlmk element 844 the page server then obtains the associated application ED 64 and link FD 54, and determines, via the DNS, the network address of the application server hosting the application 71 The page server uses the pen ED 61 to obtain the correspondmg user ED 60 from the registration server 1 1 and then allocates a globally unique hyperlink request ID 52 and builds a hyperlink request 934 The hyperlmk request class diagram is shown m Figure 44 The hyperlink request records the IDs of the requesting user and pnnter, and identifies the clicked hyperlink mstance 862 The page server then sends its own server D 53, the hyperlink request ID, and the link ED to the application The application produces a response document according to application-specific logic, and obtains a document ID 51 from an ED server 12 It then sends the document to the page server 10b responsible for the document's newly allocated D, together with the requesting page server's ED and the hyperlink request ED The second page server sends the hyperlink request ED and application ED to the first page server to obtain the coπespondmg user ED and pnnter ID 62 The first page server rejects the request if the hyperlink request has expired or is lor a different application The second page server allocates document mstance and page EDs 50, returns the newly allocated page EDs to the application, adds the complete document to its own database, and finally sends the page descnptions to the requesting pπnter The hyperlink mstance may mclude a meaningful transaction ED 55, m which case the first page server mcludes the transaction D m the message sent to the application This allows the application to establish a transaction- specific context for the hyperlink activation If the hyperlink requires a user alias, l e its "alias required" attπbute is set, then the first page server sends both the pen ID 61 and the hyperlink's application ED 64 to the registration server 11 to obtain not just the user ID - 34 - correspondmg to the pen ED but also the alias D 65 coπesponding to the application D and the user ID It mcludes the alias ED in the message sent to the application, allowing the application to establish a user-specific context for the hyperlink activation 5.3 HANDWRITING RECOGNITION PROTOCOL When a user draws a stroke on a netpage with a netpage pen, the pen communicates the stroke to the nearest netpage pπnter The stroke identifies the page and a path on the page The pnnter forwards the pen ID 61, its own pnnter ED 62, the page ED 50 and stroke path to the page server 10 m the usual way The page server loads the page descnption 5 identified bv the page D and determines which mput element's zone 58, if any the stroke mtersects Assuming the relevant mput element is a text field 878, the page server appends the stroke to the text field's digital ink After a penod of inactivity in the zone of the text field, the page server sends the pen D and the pending strokes to the registration server 11 for interpretation The registration server identifies the user correspondmg to the pen, and uses the user's accumulated handwriting model 822 to interpret the strokes as handwritten text Once it has converted the strokes to text, the registration server returns the text to the requestmg page server The page server appends the text to the text value of the text field 5.4 SIGNATURE VERIFICATION PROTOCOL Assummg the input element whose zone the stroke mtersects is a signature field 880, the page server 10 appends the stroke to the signature field's digital ink After a penod of inactivity m the zone of the signature field the page server sends the pen ID 61 and the pending strokes to the registration server 11 for venfication It also sends the application D 64 associated with the form of which the signature field is part, as well as the form ID 56 and the current data content of the form The registration server identifies the user correspondmg to the pen, and uses the user s dynamic signature biometnc 818 to venfy the strokes as the user's signature Once it has venfied the signature, the registration server uses the application ID 64 and user ED 60 to identify the user's application-specific pnvate signature kev It then uses the key to generate a digital signature of the form data, and returns the digital signature to the requestmg page server The page server assigns the digital signature to the signature field and sets the associated form's status to frozen The digital signature includes the alias D 65 of the correspondmg user This allows a smgle form to capture multiple users' signatures 5.5 FORM SUBMISSION PROTOCOL A preferred embodiment of a form submission protocol is shown m Figure 46 Form submission occurs via a form hyperlink activation It thus follows the protocol defined m Section 5 2, with some form-specific additions In the case of a form hyperlmk, the hyperlink activation message sent bv the page server 10 to the application 71 also contains the form ED 56 and the current data content of the form If the form contains any signature fields, then the application venfies each one by extracting the alias D 65 associated with the correspondmg digital signature and obtaining the coπesponding certificate from the registration server 1 1 5.6 COMMISSION PAYMENT PROTOCOL A preferred embodiment of a commission payment protocol is shown in Figure 47 In an e-commerce environment, fees and commissions may be payable from an application provider to a publisher on chck-throughs, transactions and sales Commissions on fees and commissions on commissions mav also be payable from the publisher to the provider of the prmter - 35 - The hvperlink request ED 52 is used to route a fee or commission credit from the target application provider 70a (e g merchant) to the source application provider 70b (l e publisher) and from the source application provider 70b to the pnnter provider 72 The target application receives the hyperlink request ID from the page server 10 when the hvperlink is first activated, as descnbed in Section 5 2 When the target application needs to credit the source application provider, it sends the application provider credit to the onginal page server together with the hyperlink request ED The page server uses the hvperlink request ED to identify the source application, and sends the credit on to the relevant registration server 11 together with the source application ED 64, its own server FD 53, and the hyperlink request ID The registration server credits the coπesponding application provider s account 827 It also notifies the application provider If the application provider needs to credit the pnnter provider, it sends the pπnter provider credit to the ongmal page server together with the hyperlink request ID The page server uses the hyperlink request ED to identify the pnnter, and sends the credit on to the relevant registration server together with the pnnter D The registration server credits the correspondmg pnnter provider account 814 The source application provider is optionally notified of the identity of the target application provider, and the pπnter provider of the identity of the source application provider 6. NETPAGE PEN DESCRIPTION 6.1 PEN MECHANICS Referring to Figures 8 and 9, the pen, generally designated by reference numeral 101, mcludes a housmg 102 m the form of a plastics moulding havmg walls 103 defining an mtenor space 104 for mounting the pen components The pen top 105 is m operation rotatably mounted at one end 106 of the housmg 102 A semi-transparent cover 107 is secured to the opposite end 108 of the housmg 102 The cover 107 is also of moulded plastics, and is formed from semi-transparent matenal in order to enable the user to view the status of the LED mounted withm the housmg 102 The cover 107 mcludes a mam part 109 which substantially suπounds the end 108 of the housmg 102 and a projecting portion 110 which projects back from the main part 109 and fits withm a correspondmg slot 111 formed m the walls 103 of the housmg 102 A radio antenna 112 is mounted behind the projecting portion 110, withm the housmg 102 Screw threads 113 surrounding an aperture 113A on the cover 107 are aπanged to receive a metal end piece 114 mcludmg correspondmg screw threads 115 The metal end piece 114 is removable to enable ink cartπdge replacement Also mounted withm the cover 107 is a tn-color status LED 1 16 on a flex PCB 117 The antenna 112 is also mounted on the flex PCB 117 The status LED 116 is mounted at the top ol the pen 101 for good all-around visibility The pen can operate both as a normal markmg ink pen and as a non-marking stylus An ink pen cartndge 118 with mb 119 and a stylus 120 with stylus mb 121 are mounted side by side within the housmg 102 Either the ink cartndge mb 119 or the stylus mb 121 can be brought forward through open end 122 of the metal end piece 114, by rotation of the pen top 105 Respective slider blocks 123 and 124 are mounted to the ink cartndge 118 and stylus 120 respectively A rotatable cam barrel 125 is secured to the pen top 105 m operation and arranged to rotate therewith The cam baπel 125 includes a cam 126 m the form of a slot within the walls 181 of the cam barrel Cam followers 127 and 128 projectmg from slider blocks 123 and 124 fit within the cam slot 126 On rotation of the cam barrel 125, the slider blocks 123 or 124 move relative to each other to project either the pen mb 119 or stylus mb 121 out through the hole 122 m the metal end piece 1 14 The pen 101 has three states of operation By turmng the top 105 through 90° steps, the three states are • Stylus 120 mb 121 out, • Ink cartπdge 118 mb 119 out, and • Neither ink cartπdge 118 mb 119 out nor stv lus 120 mb 121 out - 36 - A second flex PCB 129 is mounted on an electronics chassis 130 which sits within the housmg 102 The second flex PCB 129 mounts an infrared LED 131 for providmg mfrared radiation for projection onto the surface An image sensor 132 is provided mounted on the second flex PCB 129 for receivmg reflected radiation from the surface The second flex PCB 129 also mounts a radio frequency chip 133 which mcludes an RF transmitter and RF receiver, and a controller chip 134 for controlling operation of the pen 101 An optics block 135 (formed from moulded clear plastics) sits withm the cover 107 and projects an infrared beam onto the surface and receives images onto the image sensor 132 Power supply wires 136 connect the components on the second flex PCB 129 to battery contacts 137 which are mounted withm the cam barrel 125 A teπninal 138 connects to the battery contacts 137 and the cam baπel 125 A three volt rechargeable battery 139 sits within the cam barrel 125 m contact with the battery contacts An mduction charging coil 140 is mounted about the second flex PCB 129 to enable recharging of the battery 139 via mduction The second flex PCB 129 also mounts an infrared LED 143 and infrared photodiode 144 for detecting displacement m the cam barrel 125 when either the stylus 120 or the ink cartndge 11 is used for writing, m order to enable a determination of the force bemg applied to the surface by the pen nib 119 or stylus mb 121 The IR photodiode 144 detects light from the ER. LED 143 via reflectors (not shown) mounted on the slider blocks 123 and 124 Rubber gnp pads 141 and 142 are provided towards the end 108 of the housmg 102 to assist gnppmg the pen 101 and top 105 also mcludes a clip 142 for clipping the pen 101 to a pocket 6.2 PEN CONTROLLER The pen 101 is arranged to determine the position of its mb (stylus mb 121 or ink cartπdge nib 119) by imaging, m the infrared spectrum, an area of the surface in the vicinity of the mb It records the location data from the nearest location tag, and is aπanged to calculate the distance of the nib 121 or 119 from the location tab utilising optics 135 and controller chip 134 The controller chip 134 calculates the oπentation of the pen and the nib-to-tag distance from the perspective distortion observed on the imaged tag Utilising the RF chip 133 and antenna 112 the pen 101 can transmit the digital ink data (which is encrypted for secunty and packaged tor efficient transmission) to the computing system When the pen is m range of a receiver, the digital ink data is transmitted as it is formed When the pen 101 moves out of range, digital ink data is buffered withm the pen 101 (the pen 101 circuitry mcludes a buffer arranged to store digital ink data tor approximately 12 minutes of the pen motion on the surface) and can be transmitted later The controller chip 134 is mounted on the second flex PCB 129 in the pen 101 Figure 10 is a block diagram illustrating m more detail the architecture of the controller chip 134 Figure 10 also shows representations of the RF chip 133, the image sensor 132, the tn-color status LED 116 the ER illumination LED 131, the ER force sensor LED 143, and the force sensor photodiode 144 The pen controller chip 134 mcludes a controlling processor 145 Bus 146 enables the exchange of data between components of the controller chip 134 Flash memory 147 and a 512 KB DRAM 148 are also mcluded An analog-to-digital converter 149 is arranged to convert the analog signal from the force sensor photodiode 144 to a digital signal An image sensor mterface 152 interfaces with the image sensor 132 A transceiver controller 153 and base band cucuit 154 are also mcluded to interface with the RF chip 133 which includes an RF circuit 155 and RF resonators and mductors 156 connected to the antenna 112 The controlling processor 145 captures and decodes location data from tags from the surface via the image sensor 132 monitors the force sensor photodiode 144, controls the LEDs 116, 131 and 143, and handles short-range radio communication via the radio transceiver 153 It is a medium-performance (~40MHz) general-purpose RISC processor - 37 - The processor 145, digital transceiver components (transceiv er controller 153 and baseband cucuit 154) image sensor mterface 152 flash memory 147 and 512KB DRAM 148 are mtegrated m a smgle controller ASIC Analog RF components (RF circuit 155 and RF resonators and mductors 156) are provided m the separate RF chip The image sensor is a 215x215 pixel CCD (such a sensor is produced by Matsushita Electronic Corporation, and is descnbed m a paper by Itakura, K T Nobusada N Okusenya, R Nagayoshi, and M Ozaki "A 1mm 50k-Pιxel IT CCD Image Sensor for Miniature Camera System' IEEE Transactions on Electronic Devices, Volt 47, number 1 January 2000, which is incorporated herein bv reference) with an IR filter The controller ASIC 134 enters a quiescent state after a penod of inactivity when the pen 101 is not m contact with a surface It mcorporates a dedicated cncuit 150 which momtors the force sensor photodiode 144 and wakes up the controller 134 via the power manager 151 on a pen-down event The radio transceiver communicates m the unlicensed 900MHz band normally used bv cordless telephones, or alternatively in the unlicensed 2 4GHz mdustπal, scientific and medical (ISM) band, and uses frequency hoppmg and collision detection to provide interference-free communication In an alternative embodiment the pen mcorporates an Infrared Data Association (IrDA) mterface for short- range communication with a base station or netpage pπnter In a further embodiment, the pen 101 mcludes a pair of orthogonal accelerometers mounted m the normal plane of the pen 101 axis The accelerometers 190 are shown m Figures 9 and 10 in ghost outlme The provision of the accelerometers enables this embodiment of the pen 101 to sense motion without reference to surface location tags, allowing the location tags to be sampled at a lower rate Each location tag D can then identify an object of mterest rather than a position on the surface For example, if the object is a user mterface mput element (e g a command button), then the tag ED of each location tag withm the area of the mput element can duectly identify the input element The acceleration measured by the accelerometers m each of the x and y directions is integrated with respect to time to produce an instantaneous velocity and position Smce the starting position of the stroke is not known, only relative positions within a stroke are calculated Although position integration accumulates eπors in the sensed acceleration, accelerometers typically have high resolution and the time duration of a stroke, over which errors accumulate, is short 7. NETPAGE PRINTER DESCRIPTION 7.1 PRINTER MECHANICS The vertically-mounted netpage wallpnnter 601 is shown fully assembled m Figure 11 It pπnts netpages on LettertA4 sized media usmg duplexed 8 1 /-" Memjet™ pπnt engines 602 and 603, as shown m Figures 12 and 12a It uses a straight paper path with the paper 604 passing through the duplexed pnnt engines 602 and 603 which pπnt both sides of a sheet simultaneously, m full color and with full bleed An integral binding assembly 605 applies a stnp of glue along one edge of each pnnted sheet, allowing it to adhere to the previous sheet when pressed against it This creates a final bound document 618 which can range in thickness from one sheet to several hundred sheets The replaceable ink cartndge 627, shown m Figure 13 coupled with the duplexed pnnt engines, has bladders or chambers for storing fixative, adhesive, and cyan, magenta, yellow, black and infrared inks The cartndge also contams a micro an filter in a base moldmg The micro air filter interfaces with an air pump 638 mside the pnnter via a hose 639 This provides filtered air to the pnntheads to prevent ingress of micro particles mto the Memjet™ pπntheads 350 which might otherwise clog the pnnthead nozzles Bv incorporating the air filter within the cartndge, the operational life of the filter is effectively linked to the life of the cartndge The ink cartπdge is a fully recyclable product - 38 - with a capacity for pnntmg and gluing 3000 pages (1500 sheets) Referring to Figure 12, the motorized media pick-up roller assembly 626 pushes the top sheet directly from the media tray past a paper sensor on the first pnnt engme 602 mto the duplexed Memjet™ pnnthead assembly The two Memjet™ pπnt engmes 602 and 603 are mounted m an opposmg in-line sequential configuration along the straight paper path The paper 604 is drawn mto the first pnnt engme 602 by integral, powered pick-up rollers 626 The position and size of the paper 604 is sensed and full bleed pnntmg commences Fixative is pnnted simultaneously to aid drying m the shortest possible time The paper exits the first Memjet™ pnnt engme 602 through a set of powered exit spike wheels (aligned along the straight paper path), which act agamst a rubberized roller These spike wheels contact the 'wet' pnnted surface and continue to feed the sheet 604 into the second Memjet™ pnnt engme 603 Refeπing to Figures 12 and 12a, the paper 604 passes from the duplexed pnnt engines 602 and 603 mto the bmder assembly 605 The pπnted page passes between a powered spike wheel axle 670 with a fibrous support roller and another movable axle with spike wheels and a momentary action glue wheel The movable axle/glue assembly 673 is mounted to a metal support bracket and it is transported forward to interface with the powered axle 670 via gears by action of a camshaft A separate motor powers this camshaft The glue wheel assembly 673 consists of a partially hollow axle 679 with a rotating couplmg for the glue supply hose 641 from the ink cartndge 627 This axle 679 connects to a glue wheel, which absorbs adhesive by capillary action through radial holes A molded housing 682 surrounds the glue wheel, with an opening at the front Pivoting side moldings and sprung outer doors are attached to the metal bracket and hinge out sideways when the rest of the assembly 673 is thrust forward This action exposes the glue wheel through the front of the molded housmg 682 Tension springs close the assembly and effectively cap the glue wheel dunng peπods of inactivity As the sheet 604 passes mto the glue wheel assembly 673. adhesive is applied to one vertical edge on the front side (apart from the first sheet of a document) as it is transported down mto the binding assembly 605 7.2 PRINTER CONTROLLER ARCHITECTURE The netpage pnnter controller consists of a controlling processor 750, a factory-installed or field-installed network mterface module 625, a radio transceiver (transceiver controller 753. baseband circuit 754, RF circuit 755, and RF resonators and mductors 756), dual raster image processor (REP) DSPs 757. duplexed pnnt engme controllers 760a and 760b, flash memory 658, and 64MB of DRAM 657, as illustrated m Figure 14 The controlling processor handles communication with the network 1 and with local wireless netpage pens 101, senses the help button 617, controls the user mterface LEDs 613-616, and feeds and synchronizes the REP DSPs 757 and pnnt engine controllers 760 It consists of a medium-performance general-purpose microprocessor The controlling processor 750 commumcates with the pπnt engine controllers 760 via a high-speed senal bus 659 The RE? DSPs rastenze and compress page descnptions to the netpage printer's compressed page format Each pπnt engme controller expands, dithers and pπnts page images to its associated Memjet™ pnnthead 350 m real time (l e at over 30 pages per minute) The duplexed pnnt engine controllers pπnt both sides of a sheet simultaneously The master pπnt engine controller 760a controls the paper transport and monitors mk usage m con) unction with the master QA chip 665 and the ink cartndge QA chip 761 The pnnter controller's flash memory 658 holds the software for both the processor 750 and the DSPs 757 as well as configuration data This is copied to mam memory 657 at boot time The processor 750, DSPs 757, and digital transceiver components (transceiver controller 753 and baseband circuit 754) are mtegrated in a smgle controller ASIC 656 Analog RF components (RF cncuit 755 and RF resonators and mductors 756) are provided m a separate RF chip 762 The network mterface module 625 is separate, smce netpage - 39 - pπnters εdlow the network connection to be factory-selected or field-selected Flash memory 658 and the 2x256Mbit (64MB) DRAM 657 is also off-chip The pnnt engme controllers 760 are provided m separate ASICs A vanetv of network mterface modules 625 are provided each providmg a netpage network mterface 751 and optionally a local computer or network mterface 752 Netpage network Internet mterfaces mclude POTS modems, Hybnd Fiber-Coax (HFC) cable modems, ISDN modems, DSL modems, satellite transceivers, current and next- generation cellular telephone transceivers, and wireless local loop (WLL) transceivers Local mterfaces mclude IEEE 1284 (parallel port) lOBase-T and 100Base-T Ethernet, USB and USB 2 0, IEEE 1394 (Fuewire), and vanous emergmg home networkmg mterfaces If an Internet connection is available on the local network, then the local network mterface can be used as the netpage network mterface The radio transceiver 753 communicates in the unlicensed 900MHz band normally used bv cordless telephones, or alternatively m the unlicensed 2 4GHz mdustnal, scientific and medical (ISM) band and uses frequency hoppmg and collision detection to provide interference-free communication The pnnter controller optionally mcorporates an Infrared Data Association (IrDA) mterface for receiving data 'squirted' from devices such as netpage cameras In an alternative embodiment, the pnnter uses the IrDA mterface for short-range communication with suitably configured netpage pens 7.2.1 RASTERIZATION AND PRINTING Once the mam processor 750 has received and venfied the document s page layouts and page objects, it runs the appropnate REP software on the DSPs 757 The DSPs 757 rastenze each page descπption and compress the rastenzed page image The mam processor stores each compressed page image m memory The simplest way to load-balance multiple DSPs is to let each DSP rastenze a separate page The DSPs can always be kept busy since an arbitrary number of rastenzed pages can, m general, be stored in memory This strategy only leads to potentially poor DSP utilization when rastenzmg short documents Watermark regions in the page descπption are rastenzed to a contone-resolution bi-level bitmap which is losslessly compressed to negligible size and which forms part of the compressed page image The infrared (IR) layer of the pπnted page contains coded netpage tags at a density of about six per mch Each tag encodes the page ED, tag ED, and control bits, and the data content of each tag is generated dunng rasterization and stored m the compressed page image The mam processor 750 passes back-to-back page images to the duplexed pnnt engme controllers 760 Each pnnt engine controller 760 stores the compressed page image in its local memory, and starts the page expansion and pnntmg pipeline Page expansion and pπnting is pipelined because it is unpractical to store an entire 1 14MB bi-le el CMYK+IR page image m memory 7.2.2 PRINT ENGINE CONTROLLER The page expansion and pnntmg pipeline of the pnnt engine controller 760 consists of a high speed EEEE 1394 senal mterface 659, a standard JPEG decoder 763, a standard Group 4 Fax decoder 764 a custom halftoner/compositor unit 765 a custom tag encoder 766, a line loader/formatter unit 767, and a custom mterface 768 to the Memjet™ pnnthead 350 The pnnt engme controller 360 operates m a double buffered manner While one page is loaded mto DRAM 769 via the high speed senal mterface 659, the previously loaded page is read from DRAM 769 and passed through the pπnt engine controller pipeline Once the page has finished pnntmg, the page just loaded is pnnted while another page is loaded The first stage of the pipeline expands (at 763) the JPEG-compressed contone CMYK layer expands I at - 40 - 764) the Group 4 Fax-compressed bi-level black layer, and renders (at 766) the bi-level netpage tag layer accordmg to the tag format defined m section 1 2, all m parallel The second stage dithers (at 765) the contone CMYK layer and composites (at 765) the bi-level black layer over the resulting bi-level CMYK laver The residtant bi-level CMYK+ER dot data is buffered and formatted (at 767) for pnntmg on the Memjet™ pπnthead 350 via a set of lme buffers Most of these lme buffers are stored m the off-chip DRAM The final stage pπnts the six channels of bi-level dot data (mcludmg fixative) to the Memjet™ pnnthead 350 via the pnnthead mterface 768 When several pπnt engme controllers 760 are used in unison, such as m a duplexed configuration, they are synchronized via a shared lme sync signal 770 Onlv one pnnt engme 760, selected via the external master/slave pm 771, generates the lme sync signal 770 onto the shared lme The pnnt engme controller 760 contams a low-speed processor 772 for synchronizing the page expansion and rendenng pipeline, configuring the pnnthead 350 via a low-speed senal bus 773, and controlling the stepper motors 675, 676 In the 8 1 /-" versions of the netpage pnnter, the two pnnt engmes each prints 30 Letter pages per mmute along the long dimension of the page (1 1"), giving a lme rate of 8 8 kHz at 1600 dpi In the 12" versions of the netpage pπnter, the two pπnt engines each prints 45 Letter pages per mmute along the short dimension of the page (8 1 /-"), givmg a lme rate of 10 2 kHz These lme rates are well within the operating frequency of the Memjet™ pπnthead which m the cuπent design exceeds 30 kHz 8 DIRECTORY NAVIGATION A duectory is an organized list of named objects It may be presented m many ways sorted alphabetically, arranged mto named groups or topics, etc The default presentation is specific to each kmd of directory A directory may also be searched For the purposes of navigation usmg a netpage, an n-ary mdex tree is built above the duectory, with each node containing enough mdex entnes to fill two pnnted pages (I e a double-sided sheet) If two pages hold k entnes, and the entire duectory contains m entnes, then the number of levels in the index is log*m For example, if two pages hold 200 entnes, and the entire duectory represents a global telephone directory containing six billion entnes, then the number of levels m the index is five, and a user can locate a desued entry m the directorv bv pnntmg five sheets 8.1 APPLICATION DRAWING NOTATION An application user interface flow is illustrated as a collection ol documents linked bv command aπows A command arrow mdicates that the target document is pnnted as a result of the user pressmg the corresponding command button on the source page Some command arrows are labelled with multiple commands separated by slashes (7's), indicating that any one of the specified commands causes the target document to be printed Although multiple commands may label the same command arrow, they typically have different side-effects In application terms, it is important to distinguish between netpage documents and netpage forms Documents contain pπnted information, as well as command buttons which can be pressed by the user to request further information or some other action Forms, m addition to behavmg like normal documents, also contam mput fields which can be filled in by the user They provide the system with a data mput mechanism It is also useful to distinguish between documents which contain genenc mformation and documents which contain mformation specific to a particular rnteraction between the user and an application Genenc documents may be pre-pnnted publications such as magazines sold at news stands or advertismg posters encountered m public places Forms may also be pre-pnnted, mcludmg, for example, subscnption foims encountered m pre-pnnted publications They may, of course, also be generated on-the-fly by a netpage pnnter m response to user requests User-specific documents and forms are normally generated on the flv bv a netpage pπnter m response to user requests Figure 48 shows a genenc document 990, a genenc form 991 a user- - 41 - specific document 992 and a user-specific form 993 Netpages which participate m a user mterface flow are further descnbed bv abstract page layouts A page layout mav contain vanous kmds of elements, each of which has a umque style to differentiate it from the others As shown m Figure 49, these mclude fixed mformation 994, vanable information 995, mput fields 996 command buttons 997, and draggable commands 998 When a user mterface flow is broken up mto multiple diagrams, anv document which is duplicated is shown with dashed outlines m all but the mam diagram which defines it 8.2 DIRECTORY NAVIGATION An mdexed duectory class diagram is shown m Figure 50, by way of example Each mdex entry 500 is either an index node entry 501 or a directory entry 502 representing a duectory object 503, with the mdex entry 500 itself representing one of a possible number of entnes of a higher-level mdex node 504 The layout of the genenc duectory index page 520 is shown m Figure 51 Each mdex node 504 is descnbed by an entry 518 on the index page which specifies the starting and endmg names on the double-sided page it is linked to, separated by "to' , e g "Aardvark to Axolotl", "Ayatollah to Bernoulli' , etc Each entry 518 acts as a hyperlink to the coπespondmg lower-level mdex page 520 representmg the lower-level mdex node 504 If the entire directory fits on two pages, then it is presented duectly without an intervening mdex tree The presentation of the mdex entnes of a terminal (bottom-level) mdex node m a terminal mdex page 521 , l e a node which refers to actual named objects, is specific to each land of duectory Each page contams a <top> button 511 which prints the root node of the mdex, an <up> button 512 which prints the page's parent node m the mdex and <first>, <prevιous>, <next> and <last> buttons 513 to 516 which pnnt the first, previous, next and last nodes, respectively , of the page's mdex level Particular navigation buttons don't appear if they have no meanmg for the current page, e g the page for the first mdex node m an mdex level doesn't have <first> and <prevιous> buttons Each page also contams a <search> button 517 which generates a search from which allows the directory to be searched The contents of the search form are specific to each kind of directory The directorv navigation user mterface flow is illustrated m Figure 52, where the navigation functions of buttons 511 to 516 are illustrated m relation to a duectory mdex 520 and a terminal directory mdex 521 The navigation mav result m a specific directory object 522 being pnnted A similar result may be achieved by conducting a search 523, usmg the search button 517 Ol course, if the search results are ambiguous a list of matches 524 is provided for the user to select an appropnate result CONCLUSION The present invention has been descnbed with reference to a prefeπed embodiment and number of specific alternative embodiments However, it will be appreciated by those skilled m the relevant fields that a number of other embodiments, differing from those specifically descπbed, will also fall withm the spint and scope of the present mvention Accordmgly, it will be understood that the invention is not mtended to be limited to the specific embodiments descπbed in the present specification, mcludmg documents incorporated by cross-reference as appropnate The scope of the mvention is only limited by the attached claims

Claims: - 42 - CLAIMS 1 A method of enabling navigation of a duectory'- mcludmg pπnting a document containing a list of duectory entnes corresponding to at least one node of an mdex of the directory, with at least one user mteractive element which enables a user to mdicate a request for further directory information by interactmg with the element usmg a sensmg device which is adapted to transmit request data to a computer svstem, and pnntmg the further duectory mformation on a document 2 A method as claimed m claim 1 , wherem the further directory information mcludes a list of entnes corresponding to at least one further node of the index 3 A method as claimed in claim 2, wherem interacting with the at least one user mteractive element corresponds to an operation of movmg to one of a first, previous, next or last node in the mdex 4 A method as claimed in claim 2. wherem the further directory information is pnnted on a double- sided page 5 A method as claimed in claim 1 , wherein the further directorv mformation includes a list of further nodes in the duectory mdex 6 A method as claimed in claim 5, wherem interacting with the at least one user mteractive element corresponds to an operation of moving to one of a parent, child or root node of the index 7 A method as claimed in claim 1 , wherem the at least one user interactive element facilitates searching of the directory 8 A method as claimed m claim 1 , mcludmg usmg the sensmg device to select an individual entry in the list, the selection bemg identified in the computer svstem to facilitate pnntmg of details of the coπespondmg mdex node or directory object 9 A method as claimed m claim 1 , wherein the document includes coded data mdicative of an identity of the document and of the at least one interactive element, and wherem the method mcludes receivmg, m the computer system, indicating data from the sensing device regarding the identity of the document and a position of the sensmg device relative to the document in order to identify the document and determine when the sensmg device is used to mteract with the element 10 A method as claimed m claim 9, mcludmg receiving, in the computer system, movement data regarding movement of the sensmg device relative to the document 11 A method as claimed m claim 10, mcludmg the sensmg device sensmg its movement relative to the document using the coded data, and identifying the request m the computer system from the movement bemg at least partially withm a zone associated with the mteractive element 12 A method as claimed m claim 9, wherem the document is pnnted on a surface of a surface defining structure at the same time as the coded data is pnnted on the surface 13 A method as claimed in claim 9, which includes pπnting the coded data to be substantially invisible m the visible spectrum 14 A method as claimed in claim 9, mcludmg retaining a retnevable record of the pnnted document, the document bemg retnevable using the identity data as contained in the coded data 15 A method as claimed in claim 1 , wherem the sensmg device mcludes an identification code specific to a particular user and the method mcludes momtonng use of the sensing device m the computer system 16 A system for enablmg navigation of a duectory, including a computer svstem for formatting a document with a list of directory entnes coπespondmg to at least one - 43 - node of an mdex of the duectory and at least one user mteractive element to enable a user to request further directory information, a pnnter for pnntmg the document, and a sensmg device for mteracting with the element and transmitting request data to the computer system to facilitate the further mformation bemg sent from the computer system to the pnnter for pπnting m a further document 17 A system as claimed in claim 16, wherem the further duectory information mcludes a list of entnes coπespondmg to at least one further node of the index 18 A system as claimed m claim 17, wherem the element is associated with an operation of movmg to one of a first, previous, next or last node m the mdex 19 A system as claimed m claim 17, wherem the further directory information is pnnted on a double- sided page 20 A system as claimed m claim 16, wherem the further directorv information includes a list of further nodes in the directory 21 A svstem as defined m claim 20, wherem the element is associated with an operation of mov g to one of a parent, child or root node of the mdex 22 A svstem as claimed m claim 16, wherem the element is associated with a search function to facilitate searching of the duectory 23 A system as claimed m claim 16, wherem the sensing device is adapted to select an individual entry in the document and the computer system is aπanged to send details of the coπespondmg mdex node or duectory object to the pnnter for pnntmg 24 A svstem as claimed in claim 14, wherein the document mcludes coded data mdicative ot an identity of the document and of the at least one mteractive element 25 A system as claimed m claim 24, wherem the computer system is adapted to receive movement data regarding movement of the sensmg device relative to the document and mterpret said movement of the sensmg device as it relates to said at least one element the sensing device, when moved relative to the document sensmg the data regarding said at least one element usmg at least some of the coded data and generating the data regarding its own movement relative to the document 26 A system as claimed m claim 25, wherem sensmg device senses its own movement relative to the document using the coded data 27 A system as claimed m claim 16, wherein the sensmg device mcludes an identification code specific to a particular user and the computer system is arranged to monitor the use of the sensmg device 28 A svstem as claimed m claim 16, wherein the sensmg device includes a markmg mb 29 A system as claimed m claim 16, wherem the document is pnnted on a surface of a surface-defining structure and wherem the pπnter pπnts the document on demand 30 A system as claimed in claim 28, wherein the pπnter is aπanged to pπnt the coded data at the same tune as pnntmg the document on a surface-defining structure 31 A system as claimed m claim 28, wherem the coded data is substantially invisible m the visible spectrum 32 The system as claimed m claim 28, mcludmg a database lor keepmg a retnevable record of each document generated, each document bemg retnevable bv usmg its identity, as mcluded in its coded data 33 The svstem as claimed m claim 16, wherem the pnnter mcludes a binding means for bmdmg the document m the event the document includes a plurality of pages

Inventors: LAPSTUN PAUL, LAPSTUN, PAUL
Applicants: LAPSTUN PAUL, SILVERBROOK KIA, SILVERBROOK RES PTY LTD, LAPSTUN, PAUL, SILVERBROOK RESEARCH PTY LTD, SILVERBROOK, KIA
Application year: 2000
Main classification: G06F17
IPC codes: G06F3, G06F12, G06F13, G06F17, G06K17