METHOD AND SYSTEM FOR DELIVERY OF A SECURE DOCUMENT

Abstract: A method and system for issuing secure documentation, such as tickets or coupons. The method includes producing a secure document having printed information and coded data thereon, the coded data including a unique identifier indicative of the secure document. A correspondence is recorded, in a computer system, between the secure document and validity status and/or authenticity information relating to the document. A sensing device is provided, adapted to sense the coded data on the secure document. The sensing device is further adapted for communication with said computer system, whereby the validity status and/or authenticity of said document can be determined by sensing said coded data to obtain the secure document unique identifier and communicating with the computer system to determine the validity status and/or authenticity information corresponding thereto. The secure document can be produced on demand in response to a request from a user to an issuer by way of the computer system, wherein the secure document is produced at the user's premises.

Description: - 1 - METHOD AND SYSTEM FOR DELIVERY OF A SECURE DOCUMENT FIELD OF INVENTION The present invention relates generally to methods, systems and apparatus for interacting with computers by means of printed matter and sensing devices More particularly, the invention relates to delivery of a secure document such as a ticket or coupon or the like, utilizing such methods, systems and apparatus The invention has been developed primarily to allow a large number of distributed users to interact with networked information via printed matter and to obtain interactive pπnted matter on demand via 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/AU00/00521, PCT/AU00/00523, PCT/AU00/00524, PCT/AU00/00525, PCT/AUOO/00526, PCT/AU00/00527, PCT/AU00/00528, PCT/AU00/00529, PCT/AU00/00530, PCT/AU00/00531 , PCT/AU00/00532, PCT/AU00/00533, PCT/AU00/00534, PCT/AU00/00535, PCT/AU00/00536, PCT/AU00/00537, PCT/AU00/00538, PCT/AU00/00539, PCT/AU00/0O540, PCT/AU00/00541 , PCT/AU00/00542, PCT/AU00/00543, PCT/AUOO/00544, PCT/AU00/00545, PCT/AU00/00547, PCT/AU00/00546, PCT/AU00/00554, PCT/AU00/00556, PCT/AU00/00557, PCT/AU00/00558, PCT/AU00/00559, PCT/AU00/00560, PCT/AU00/00561, PCT/AU00/00562, PCT/AU00/00563, 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/AUOO/00573, PCT/AUOO/00574, PCT/AU00/00575, P( 1 'AUOO/00576, PCT/AUOO/00577, PCT/AUOO/00578, PCT/AU00/00579, PCT/AUOO/00581 , PCT/AU00/00580, PCT/AUOO/00582, PCT/AUOO/00587, PCT/AU00/00588, PCT/AU00/00589, PCT/AU00/00583, 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 A secure document such as a ticket or coupon is potentially validated, verified a number of times, and finally cancelled during its lifetime Although the status of the document may be recorded in a computer system, correlating the status of the paper document with its computer record is normally a manual process OBJECT It is an object of the invention to combine advantages of paper-based documents with online document status management RECTIFIED SHEET (RULE 91) ISA/EP - 1a - SUMMARY OF INVENTION In accordance with the invention, there is provided a method for providing secure documentation, including the steps of: providing a secure document having printed information and coded data thereon, the coded data including a unique identifier indicative of the secure document; recording, in a computer system, a coπespondence between the secure document and validity status and/or authenticity information relating to the document; and providing a sensing device adapted to sense said coded data on the secure document, the sensing device being further adapted for communication with said computer system, whereby the validity status and/or authenticity of said document can be determined by sensing said coded data to obtain the secure document unique identifier and RECTIFIED SHEET (RULE 91) ISA/EP - 2 - commumcating with the computer system to detemune the validity status and/or authenticity mformation corresponding thereto In a preferred form of the mvention the secure document mcludes first and second pπnted patterns on opposed sides of a sheet matenal of the secure document, the first and second pπnted patterns forming a watermark pattern when viewed through the sheet matenal Preferably the coded data is pnnted on the secure document so as to be substantially invisible m the visible spectrum In one form of the mvention the secure document is pπnted on demand For example, the secure document can be pπnted on demand m response to a request from a user through said computer system, wherem the pπnted information mcludes a photographic representation of the requesting user The secure document may be produced as part of an electronic commerce transaction For example, the secure document may be m the form of a ticket or coupon In a preferred implementation of the mvention the validity status and/or authenticity mformation mcludes an indication of whether the ticket or coupon has been canceled by its issuer In accordance with the present mvention, there is also provided a method of issuing secure documentation, such as tickets or coupons, mcludmg the steps of producmg a secure document havmg pπnted information and coded data thereon, the coded data mcludmg a umque identifier mdicative of the secure document, registering, m a computer system, a correspondence between the secure document and validity status and/or authenticity information relating to the document, and providmg a sensmg device adapted to sense said coded data on the secure document, the sensmg device bemg further adapted for communication with said computer system, whereby the validity status and/or authenticity of said document can be determined by sensmg said coded data to obtain the secure document umque identifier and commumcating with the computer system to determine the validity status and/or authenticity mformation correspondmg thereto, wherem the secure document is produced on demand m response to a request from a user to an issuer by way of said computer system, and wherem the secure document is produced at the user s premises In one form of the mvention the secure document mcludes first and second pnnted patterns on opposed sides of a sheet matenal of the secure document, the first and second pnnted patterns forming a watermark pattern when viewed through the sheet matenal Preferably the coded data is prmted on the secure document so as to be substantially invisible m the visible spectrum In one implementation of the mvention, the pnnted information mcludes a photographic representation of the requesting user The secure document may be produced as part of an electronic commerce transaction In one form of the mvention, the validity status and/or authenticity information mcludes an indication of whether the ticket or coupon has been canceled by its issuer In accordance with the present mvention, there is also provided a secure documentation system mcludmg at least one terminal device adapted to produce a secure document having pnnted information and coded data thereon, the coded data mcludmg a umque identifier mdicative of the secure document, a computer system coupled to communicate with the at least one terminal device and havmg a stored correspondence between the secure document and validity status and/or authenticity uiformation relating to the document, and at least one sensmg device adapted to sense said coded data on the secure document, the sensmg device bemg further adapted for commumcation with said computer system to obtam the stored validity status and/or authenticity information correspondmg to the secure document Preferably the teπrunal device mcludes a pπnter for pnntmg the pnnted documentation and the coded data The teπninal device may be controllable by a user to produce a secure document on demand, wherem the coded data is supplied from an issuer through said computer system to the termmal device In one form of the mvention, the secure document mcludes first and second pπnted patterns on opposed sides of a sheet matenal of the secure document, the first and second pnnted patterns forming a watermark pattern when viewed through the sheet matenal Preferably the coded data is pnnted on the secure document so as to be substantially invisible m the visible spectrum In one implementation of the mvention the secure document is pπnted on demand m response to a request from a user through said computer system, wherem the pπnted information mcludes a photographic representation of the requesting user The secure document may be produced as part of an electronic commerce transaction For example, the secure document may be in the form of a ticket or coupon In one form of the mvention the validity status and/or authenticity information mcludes an indication of whether the ticket or coupon has been canceled by its issuer BRIEF DESCRIPTION OF DRAWINGS Preferred and other embodiments of the mvention will now be descnbed, by way of non-limiting example only, with reference to the accompanying drawings, m 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 mteraction 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 pπnters interconnected via a network, Figure 4 is a schematic view of a high-level structure of a pnnted netpage and its online page descnption, 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 processmg 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 m 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 pπnter of Figure 11, Figure 12a is an enlarged portion of Figure 12 showing a section of the duplexed pnnt engmes and glue wheel assembly, Figure 13 is a detailed view of the ink cartndge, ink, an and glue paths, and pπnt engmes of the netpage pπnter of Figures 11 and 12, Figure 14 is a schematic block diagram of a pnnter controller for the netpage pπnter shown m Figures 11 and 12, Figure 15 is a schematic block diagram of duplexed pπnt engine controllers and Memjet™ pπntheads associated with the pπnter controller shown m Figure 14, - 4 - 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 18 is a perspective view of a small part of an array of Memjet™ pπnting elements, Figure 19 is a senes of perspective views illustrating the operatmg cycle of the Memjet™ pnntmg element shown m 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 hyperimked 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 mput 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, and Figure 47 is a schematic view of a commission payment protocol DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS Note Memjet™ is a trade mark of Silverbrook Research Pty Ltd, Australia In the prefeπed embodiment, the mvention is configured to work with the netpage networked computer system, a detailed overview of which follows It will be appreciated that not every implementation will necessanly embody all or even most of the specific details and extensions discussed below in relation to the basic system However, the system is descnbed m its most complete foπn to reduce the need for external reference when attempting to understand the context in which the preferred embodiments and aspects of the present invention operate - 5 - In bπef summary, the preferred form of the netpage system employs a computer mterface 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 m such a way that a local query on the mapped surface yields an unambiguous map reference both within the map and among different maps The computer system can contam information about features on the mapped surface, and such mformation can be retneved based on map references supplied by a sensmg device used with the mapped surface The information thus retπeved can take the form of actions which are initiated by the computer system on behalf of the operator m response to the operator's mteraction with the surface features In its preferred form, the netpage system relies on the production of, and human mteraction with, netpages These are pages of text, graphics and images pnnted on ordinary paper, but which work like mteractive web pages Information is encoded on each page usmg ink which is substantially invisible to the unaided human eye The mk, 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 mformation from the network or to signed 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 securely authorized As illustrated m Figure 1 , a pnnted netpage 1 can represent a mteractive form which can be filled m by the user both physically, on the pnnted page, and "electronically", via commumcation 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 ink The correspondmg page descπption 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 mteractive element (l e text field or button in the example), to allow the netpage system to correctly mterpret mput via the netpage The submit button 6, for example, has a zone 7 which corresponds to the spatial extent of the corresponding graphic 8 As illustrated m Figure 2, the netpage pen 101, a preferred form of which is shown in Figures 8 and 9 and descnbed m more detail below, works m conjunction with a netpage pnnter 601, an Internet-connected pnntmg appliance for home, office or mobile use The pen is wueless 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 pπnted at high quality as mteractive netpages Unlike a personal computer, the netpage pπnter 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 tabletop, desktop, portable and miniature versions Netpages pπnted at then pomt of consumption combme the ease-of-use of 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 pπnted netpage 1 and commumcates, 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 cucumstances, the page server sends a correspondmg message to application computer software running on a netpage application server 13 The application - 6 - server may m turn send a response which is pπnted on the onginating pnnter The netpage system is made considerably more convenient 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 preferred form, a netpage publication has the physical characteπstics of a traditional newsmagazme, such as a set of letter-size glossy pages pπnted m full color on both sides, bound together for easy navigation and comfortable handling The netpage pπnter exploits the growing availability of broadband Internet access Cable service is available to 95% of households m the Umted States, and cable modem service offering broadband Internet access is already available to 20% of these The netpage pnnter can also operate with slower 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 pπnter 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 pπnters via pomtcasting and multicasting Internet protocols Personalized publications are filtered and formatted accordmg to individual user profiles A netpage pπnter can be configured to support any number of pens, and a pen can work with any number of netpage pπnters In the preferred implementation, each netpage pen has a umque identifier A household may have a collection of colored netpage pens, one assigned to each member of the family This allows each user to maintam 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 authonzed 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 fingerprint scanmng, 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 pπnter 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 descπbed usmg a U fied Modelmg Language (UML) class diagram A class diagram consists of a set of object classes connected by relationships, and two kmds of relationships are of mterest here associations and generalizations An association represents some land of relationship between objects, l e between instances of classes A generalization relates actual classes, and can be understood m the following way if a class is thought of as the set of all objects of that class, and class A is a generalization of class B, then B is simply a subset of A The UML does not duectly support second-order modelling - 1 e classes of classes Each class is drawn as a rectangle labelled with the name of the class It contains a list of the attributes of the class, separated from the name by a hoπzontal lme, and a list of the operations of the class, separated from the attribute list by a hoπzontal 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 joining two classes, with an arrow (m the form of an open tπangle) at the generalization end When a class diagram is broken up mto multiple diagrams, any class which is duplicated is shown with a dashed outline m all but the mam diagram which defines it It is shown with attnbutes only where it is defined 1.1 NETPAGES Netpages are the foundation on which a netpage network is built They provide a paper-based user mterface to published mformation and mteractive services A netpage consists of a pπnted page (or other surface region) invisibly tagged with references to an online descnption of the page The online 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 sunultaneously captured and processed by the netpage system Multiple netpages can share the same page descπption However, to allow mput through otherwise identical pages to be distinguished, each netpage is assigned a umque 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 pπnted tag The tag identifies the umque page on which it appears, and thereby mduectly identifies the page descnption The tag also identifies its own position on the page Characteπstics of the tags are descnbed m more detail below Tags are pnnted m infrared-absorptive ink on any substrate which is infrared-reflective, such as ordinary 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 m 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 pπnter 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 ID and position on every mteraction with the page, smce the mteraction is stateless Tags are error-correctably encoded to make them partially tolerant to surface damage The netpage page server maintains a umque page mstance for each pπnted netpage, allowing it to maintain a distinct set of user-supplied values for mput fields m the page descπption for each pπnted netpage The relationship between the page descnption, the page mstance, and the prmted netpage is shown m Figure 4 The page mstance is associated with both the netpage pnnter which pnnted it and, if known, the netpage user who requested it 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 within 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 sensmg device havmg to refer to a descπption of the region A netpage pen may, for example, illuminate an "active area" LED when m the zone of a hyperlmk - 8 - As will be more clearly explained below, m a preferred embodiment, each tag contams an easily recognized mvanant structure which aids initial detection, and which assists m 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 smgle click on the page It is important that the pen recognize the page ID and position on every mteraction with the page, smce the mteraction is stateless In a preferred embodiment, the region to which a tag refers comcides 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 mch, 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 usmg abutting regions and maps The 100-bit region ID allows 2 100 (~10 30 or a million tnlhon tπllion) different regions to be umquely 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 errors to be corrected per codeword, l e it is tolerant of a symbol error rate of up to 33% per cot 1 - w ord Each 4-bit symbol is represented in a spatially coherent way m the tag, and the symbols of the six codewords are mterleaved spatially within the tag This ensures that a burst error (an error affecting multiple spatially adjacent bits) damages a minimum number of symbols overall and a minimum number of symbols m any one codeword, thus maximising the likelihood that the burst error can be fully corrected 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 sensmg device such as the netpage pen to detect the tag and infer 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 pπnted at 1600 dots per mch this yields 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 Since the quiet area is also contributed by 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 sensing device to initially detect the tag The πng is easy to detect because it is rotationally mvanant and because a sunple correction of its aspect ratio removes most of the effects of perspective distortion An onentation axis 16 allows the sensmg device to detemune the approximate planar onentation of the tag due to the yaw of the sensor The onentation axis is skewed to yield a umque - 9 - oπentation 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 oπentation of the tag relative to the sensor All target structures are redundantly large to improve theu lrnmunity to noise The overall tag shape is cucular This supports, amongst other things, optimal tag packing on an irregular tnangular gnd In combination with the cucular detection nng, this makes a circular arrangement of data bits withm the tag optimal To maximise its size, each data bit is represented by a radial wedge m the form of an area bounded by two radial lmes and two concentnc circular arcs Each wedge has a muumum 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 πununum 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 Assummg a circular tag shape, the muumum 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 decoding performed by a sensmg device such as the netpage pen is shown m 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 (I 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 then nature mvanant of position, and can be easily made mvanant of scale, aspect ratio and rotation The nng 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 πng'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 πng's normalizations 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 tlurd order moment is required to disambiguate the two 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 then positions - 10 - are computed based on their known spatial relationships to the nng and axis targets, the aspect and rotation of the πng, and the rotation of the axis Matching proceeds by applying the πng's normalizations to each shape's moments Once then second-order moments are normalized the cucular perspective targets are easy to recognize, and the target closest to each estimated position is taken as a match The oπgmal centroids of the four perspective targets are then taken to be the perspective-distorted co ers 31 of a square of known size m tag space, and an eight-degree-of-freedom perspective transform 33 is inferred (at 32) based on solving the well-understood equations relating the four tag-space and image- space pomt parrs The inferred tag-space to image-space perspective transform is used to project (at 36) each known data bit position m tag space mto image space where the real- valued position is used to bilmearly interpolate (at 36) the four relevant adjacent pixels m the mput image The previously computed unage 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 nng target 15 is onlv sought m 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 processmg power and ideally a non-muumal field of view 193, an alternative strategy mvolves seeking another tag m the current unage 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 mb m the region, as well as the over-ill onentation 35 of the pen, is then infeπed (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 m 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 within the region 1.2.7 Tagging Schemes Two distinct surface coding schemes are of interest, both of which use the tag structure descnbed earlier m this section The preferred coding scheme uses "location-indicating" tags as afready discussed An alternative coding scheme uses object-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 - 11 - therefore tπvially support the capture of an absolute pen path m the zone of a particular user mterface element An object-indicating tag contams a tag ID which directly identifies a user mterface element in the page descπption 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 mdistinguishable 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 within a stroke can be unambiguously determined With either tagging scheme, the tags function m cooperation with associated visual elements on the netpage as user mteractive elements in that a user can mteract with the pπnted 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 m the netpage system 1.3 DOCUMENT AND PAGE DESCRIPTIONS A preferred 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 termmal elements 839 are associated with content objects 840 such as text objects, text style objects, unage objects, etc Once the document is pnnted on a pnnter with a particular page size and accordmg to a particular user's scale factor preference, the document is pagmated and otherwise formatted Formatted termmal elements 835 will m some cases be associated with content objects which are different from those associated with then correspondmg terminal elements, particularly where the content objects are style-related Each pnnted mstance of a document and page is also descπbed separately, to allow mput captured through a particular page mstance 830 to be recorded separately from input captured through other instances of the same page descπption 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 may be requesting a copy through a pnnter with a different page size, for example Conversely, the presence of the formatted document descnption on the page server allows the page server to efficiently mterpret 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 termmal 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 mput fields A document mstance 831 corresponds to a formatted document 834 It consists of a set of page instances 830, each of which coπesponds to a page descnption 5 of the formatted document Each page mstance 830 descπbes a smgle unique pnnted netpage 1, and records the page ID 50 of the netpage A page mstance is not part of a document mstance if it represents a copy of a page requested m isolation A page mstance consists of a set of terminal element instances 832 An element mstance only exists if it records instance-specific information Thus, a hyperlink mstance exists for a hyperlmk element because it records a transaction ID 55 which is specific to the page mstance, and a field mstance exists for a field element because it records mput specific to the page mstance An element mstance does not exist, however, for static elements such as textflows A terminal 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 with 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 mstance has a background field 833 which is used to record any digital ink captured on the page - 12 - which does not apply to a specific mput element In the preferred form of the mvention, a tag map 811 is associated with each page mstance to allow tags on the page to be translated mto locations on the page 1.4 THE NETPAGE NETWORK In a prefeπed 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 m Figure 3 The netpage registration server 11 is a server which records relationships between users, pens, pπnters, applications and publications, and thereby authonzes vanous network activities It authenticates users and acts as a sig ng proxy on behalf of authenticated users in application transactions It also provides handwnting recogmtion services As descnbed above, a netpage page server 10 maintains persistent mformation about page descnptions and page instances The netpage network mcludes any number of page servers, each handlmg a subset of page instances Smce a page server also maintains user mput values for each page mstance, clients such as netpage pnnters send netpage mput duectly to the appropnate page server The page server interprets any such mput relative to the descnption of the corresponding 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 pπnter 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 handlmg the correspondmg page mstance 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 pπnters They are descnbed m detail in Section 2 Netpage servers can be hosted on a vanety 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 of the functionality provided by netpage servers, and m particular the functionality provided by the ID server and the page server, can also be provided αrrectly 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 pπnter 601 is an appliance which is registered with the netpage system and prints netpage documents on demand and via subscnption Each pπnter has a umque pπnter 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 prmter contams no persistent storage As far as a user is concerned, "the network is the computer" Netpages function interactively across space and tune with the help of the distributed netpage page servers 10, mdependently of particular netpage pnnters The netpage pnnter receives subscnbed netpage documents from netpage publication servers 14 Each document is distnbuted 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' pπnters and the appropnate page servers The netpage publication server optimizes the segmentation of document content mto pomtcasts and multicasts After receiving the pomtcast of a document's page layouts, the pπnter knows which multicasts, if any, to listen to - 13 - Once the pπnter has received the complete page layouts and objects that define the document to be pπnted, it can pπnt the document The pπnter rasteπzes and pπnts odd and even pages simultaneously on both sides of the sheet It contams duplexed pπnt engme controllers 760 and pπnt engmes utilizing Memjet™ pπntheads 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 (RIP) consists of one or more standard DSPs 757 running in parallel The duplexed pπnt engme controllers consist of custom processors which expand, dither and pπnt page images m real tune, synchronized with the operation of the prmtheads in the pπnt engmes 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 pπnts netpages on sheets of paper More specialised netpage pπnters may pnnt onto more specialised surfaces, such as globes Each pπnter 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 811 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 correctly interpreted Figure 2 shows the netpage pπnter class diagram, reflecting printer-related information mamtamed by a registration server 11 on the netpage network A preferred embodiment of the netpage pπnter is descπbed m greater detail m Section 6 below, with reference to Figures 11 to 16 1.5.1 Memjet™ Printheads The netpage system can operate usmg pπnters made with a wide range of digital pπnting technologies, mcludmg thermal inkjet, piezoelectnc Inkjet, laser electrophotographic, and others However, for wide consumer acceptance, it is desuable that a netpage pnnter have the following characteπstics • photographic quality color pπnting • high quality text printing • high reliability • low pnnter cost • low ink cost • low paper cost • sunple operation • nearly silent pnntmg • high pnntmg speed • simultaneous double sided pnntmg • compact form factor • low power consumption No commercially available pπnting technology has all of these charactenstics To enable to production of pnnters with these charactenstics, the present applicant has mvented a new pnnt technology, referred to as Memjet™ technology Memjet™ is a drop-on-demand inkjet technology that mcorporates pagewidth pπntheads fabncated usmg microelectrαrnechanical systems (MEMS) technology Figure 17 shows a smgle pnntmg element 300 of a Memjet™ pπnthead The netpage wallpnnter mcorporates 168960 pnntmg elements 300 to foπn a 1600 dpi pagewidth duplex pπnter This pnnter simultaneously pπnts cyan, magenta, yellow, black, and infrared - 14 - lnks as well as paper conditioner and ink fixative The pnntmg element 300 is approximately 110 microns long by 32 microns wide Arrays of these pnntmg elements are formed on a silicon substrate 301 that mcorporates CMOS logic, data transfer, timing, and dnve cucuits (not shown) Major elements of the pnntmg 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 pan 308, the passive actuator beam pair 309, the active actuator anchor 310, the passive actuator anchor 311, and the ink inlet 312 The active actuator beam pan 308 is mechanically jomed to the passive actuator beam pair 309 at the jom 319 Both beams pans are anchored at then respective anchor points 310 and 311 The combination of elements 308, 309, 310, 311, and 319 form a cantilevered electrothermal bend actuator 320 Figure 18 shows a small part of an array of pnntmg elements 300, mcludmg a cross section 315 of a pnntmg element 300 The cross section 315 is shown without ink, to clearly show the ink inlet 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 19(a) shows the quiescent position of the ink memscus 316 pπor to pnntmg an ink droplet Ink is retained m the nozzle chamber by surface tension at the ink memscus 316 and at the fluidic seal 305 formed between the nozzle chamber 304 and the ink channel run 306 While pnntmg, the pnnthead CMOS cncuitry distributes data from the pπnt engme controller to the correct pnntmg element, latches the data, and buffers the data to dnve the electrodes 318 of the active actuator beam pan 308 This causes an electncal current to pass through the beam pan 308 for about one microsecond, resultmg m Joule heating The temperature mcrease resulting from Joule heating causes the beam pair 308 to expand As the passive actuator beam pan 309 is not heated, it does not expand, resulting m a stress difference between the two beam paus This stress difference is partially resolved by the cantilevered end of the electrothermal bend actuator 320 bendmg 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, forcing ink 321 out of the nozzle 302, and causing the mk memscus 316 to bulge The nozzle nm 303 prevents the ink memscus 316 from spreading across the surface of the nozzle chamber 304 As the temperature of the beam pans 308 and 309 equalizes, the actuator 320 returns to its ongmal position This aids m the break-off of the ink droplet 317 from the ink 321 in the nozzle chamber, as shown m 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 pπnthead is the full width of the paper (typically 210 mm) m the dnection 351 The segment shown is 04 mm long (about 02% of a complete pnnthead) When pnntmg, the paper is moved past the fixed pπnthead m the dnection 352 The pnnthead has 6 rows of interdigitated 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 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 au is pumped through the au inlets 332 and out of the nozzle guard holes dunng pnntmg To prevent ink 321 from drying, the nozzle guard is sealed while the pπnter is idle 1.6 The Netpage Pen The active sensmg device of the netpage system is typically a pen 101, which, usmg its embedded controller 134, is able to capture and decode IR position tags from a page via an unage sensor The image sensor is a solid-state - 15 - device provided with an appropnate filter to permit sensmg at only near-infrared wavelengths As descnbed m more detail below, the system is able to sense when the mb is m contact with the surface, and the pen is able to sense tags at a sufficient rate to capture human handwnting (1 e at 200 dpi or greater and 100 Hz or faster) Information captured by the pen is encrypted and wirelessly transmitted to the pnnter (or base station), the pnnter 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- marking stylus The markmg aspect, however, is not necessary for usmg the netpage system as a browsmg system, 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 mformation mamtamed by a registration server 11 on the netpage network When either mb is m contact with a netpage, the pen determines its position and oπentation relative to the page The mb is attached to a force sensor, and the force on the mb is interpreted relative to a threshold to mdicate 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, mformation 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 deteπrunes the position and onentation of its mb on the netpage by imaging, m the infrared spectrum, an area 193 of the page in 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 requued for accurate handwnting recogmtion Pen actions relative to a netpage are captured as a senes of strokes A stroke consists of a sequence of tune- 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 cucumstances, 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 tune peπod The current selection descnbes a region of a page mstance It consists of the most recent digital ink stroke captured through the pen relative to the background area of the page It is interpreted m an application-specific manner once it is submitted to an application via a selection hyperlink activation Each pen has a current mb 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 marking black ink mb or the non-marking stylus mb is current Each pen also has a current mb style 825 This is the mb style last associated with the pen by an application, e g m response to the user selecting a color from a palette The default mb style is the mb 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 reproduced m the mb style with which they are tagged Whenever the pen is withm range of a pnnter with which it can communicate, 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 decodmg a stroke relative to the page, it momentanly activates its "ok" LED A sequence of captured strokes is referred to as digital ink Digital ink forms the basis for the digital exchange of drawings and handwnting, for online recogmtion of handwπting, and for online venfication of signatures The pen is wueless and transmits digital ink to the netpage pnnter via a short-range radio link The - 16 - transπutted digital ink is encrypted for pnvacy and security and packetized for efficient transmission, but is always flushed on a pen-up event to ensure timely handling m the pπnter When the pen is out-of-range of a pnnter it buffers digital ink m internal memory, which has a capacity of over ten rninutes 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 commumcating with at any particular tune A preferred embodiment of the pen is descnbed m greater detail m Section 6 below, with 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 mteract 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 mteractive 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 correspondmg page mstance 830 It then transmits the stroke to the page server If the page was recently identified m an earlier stroke, then the pπnter may afready have the address of the relevant page server m 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 descπption the stroke mtersects It is then able to mterpret the stroke m the context of the type of the relevant element A "click" is a stroke where the distance and tune between the pen down position and the subsequent pen up position are both less than some small maximum An object which is activated by T ..hck typically requues a click to be activated, and accordingly, a longer stroke is ignored The failure of a pen action, .tich 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 tπgger 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 pπnted 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 in the hyperlink activation, and a descπption which is used when the hyperlink is recorded as a favonte or appears m the user's history The hyperlmk element class diagram is shown m Figure 29 When a hyperlmk 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 types of hyperlinks general hyperlinks 863, form hyperlinks 865, and selection hyperlinks 864, as shown in 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 correspondmg 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, - 17 - the application may 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 hyperlmk type is characterized by what information is submitted to the application The correspondmg hyperlink instance 862 records a transaction ID 55 which can be specific to the page mstance on which the hyperlmk 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 mcludes the pen's current selection 826 m a selection hyperlmk activation The system mcludes the content of the associated form mstance 868 m a form hyperlink activation, although if the hyperlmk has its "submit delta" attribute set, only mput smce the last form submission is mcluded The system mcludes an effective retum path m 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 foπn hyperlmk, to provide continuous mput to an application It can therefore be used to support a "blackboard" mteraction model, I e where mput 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 mputs through a pnnted netpage A foπn allows a user to submit one or more parameters to an application software program runmng on a server A form 867 is a group element 838 m the document hierarchy It ultimately contams a set of termmal field elements 839 A form instance 868 represents a pπnted mstance of a form It consists of a set of field instances 870 which correspond to the field elements 845 of the form Each field mstance has an associated value 871, whose type depends on the type of the correspondmg field element Each field value records mput through a particular pπnted form mstance, l e through one or more pπnted netpages The form class diagram is shown m Figure 32 Each form mstance has a status 872 which mdicates whether the form is active, frozen, submitted, void or expued A form is active when first pπnted A for 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" attribute set A foπn becomes void when the user mvokes a void form, reset form or duplicate form page command A form expues 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 mstance When the form is active or frozen, form submission is allowed Any attempt to submit a form when the form is not active or frozen is rejected, and mstead elicits an form status report Each form mstance is associated (at 59) with any form instances denved from it, thus providmg a version history 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 of a set of timestamped stroke groups 874, each 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 m 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 mk captured m a field's zone 58 is assigned to the field A checkbox field has an associated boolean value 881, as shown m Figure 35 Any mark (a tick, a cross, a stroke, a fill zigzag, etc ) captured m a checkbox field's zone causes a true value to be assigned to the field's value - 18 - 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 onlme handwπting recogmtion, and the text is assigned to the field's value Onlme handwriting recogmtion is well-understood (see for example Tappert, C , C Y Suen and T Wakahara, "The State of the Art m On-Line Handwπting Recogmtion", 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 m Figure 37 Any d gital ink captured m 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 usmg the pen user's pnvate signature key specific to the application which owns the form Onlme 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 Recogmtion, Vol 22, No 2, 1989) A field element is hidden if its "hidden" attribute 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 m the form data when the form containing the field is submitted "Editing" commands, such as stπke-throughs mdicatmg deletion, can also be recognized in form fields Because the handwnting recogmtion algonthm works "onlme" (l e with access to the dynamics of the pen movement), rather than "offline" (I 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 training phase A wnter-dependent model of handwnting is automatically generated over tune, 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 Any 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 Cucumscnption of one or more objects is generally interpreted as a selection of the cucumscπbed objects, although the actual interpretation is application-specific Table 2 summaπses these various pen mteractions with a netpage Table 2 - Summary of pen interactions with a netpage The system maintains a current selection for each pen The selection consists simply of the most recent stroke captured m the backgroimd field The selection is cleared after an mactivity timeout to ensure predictable behavior The raw digital ink captured m every field is retained on the netpage page server and is optionally - 19 - transnutted 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 onginal conversion, such as the conversion of handwntten text This can, for example, mvolve 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 ink 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 handlmg pen mput relative to a netpage The process consists of receiving (at 884) a stroke from the pen, identifymg (at 885) the page mstance 830 to which the page ID 50 m the stroke refers, retnevmg (at 886) the page descnption 5, identifymg (at 887) a formatted element 839 whose zone 58 the stroke mtersects, deter uung (at 888) whether the formatted element corresponds to a field element, and if so appending (at 892) the received stroke to the digital ink of the field value 871, interpreting (at 893) the accumulated digital mk of the field, and determuung (at 894) whether the field is part of a hyperimked group 866 and if so activating (at 895) the associated hyperlink, alternatively determuung (at 889) whether the formatted element corresponds to a hyperlmk element and if so activating (at 895) the correspondmg 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 copymg (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 accordmg to the type of the field The process consists of determuung (at 896) whether the field is a checkbox and (at 897) whether the digital ink represents a checkmark, and if so assignmg (at 898) a true value to the field value, alternatively determuung (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 assignmg (at 901) the converted computer text to the field value, alternatively determuung (at 902) whether the field is a signature field and if so veπfying (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 correspondmg form, also with the help of the registration server and usmg the pen owner's pπvate signature key relating to the correspondmg application, and assignmg (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 duectly 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 910, 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 in Figure 39 A void form command voids the correspondmg form mstance A duplicate form command voids the coπespondmg form mstance and then produces an active pπnted copy of the current form mstance with field values preserved The copy contains the same hyperlink transaction IDs as the ongmal, and so is indistinguishable from the onginal to an application A reset form command voids the correspondmg form mstance and then produces an active pπnted copy of the form mstance with field values discarded A get form status command produces a pnnted report on the status of the correspondmg form 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 hyperlmk mstance contams a transaction ID, the application has to be mvolved m producmg a - 20 - new form mstance A button requesting a new form mstance is therefore typically implemented as a hyperlmk A duplicate page command produces a pπnted copy of the coιτespondmg 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 correspondmg 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 correspondmg page mstance, mcludmg who published it, when it was pnnted, for whom it was pπnted, 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 prmted 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 theu ongmal 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 contains any forms, then the duplicate document command duplicates the forms in the same way a duplicate form command does A reset document command produces a pπnted copy of the corresponding 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 pπnted report on the status of the corresponding document mstance, mcludmg who published it, when it was pnnted, for whom it was pπnted, and the status of any forms it contams If the page server command's "on selected" attπbute is set, then the command operates on the page identified by the pen's current selection rather than on the page containing the command This allows a menu of page server commands to be pπnted If the target page doesn't contam a page server command element for the designated page server command, then the command is ignored An application can provide application-specific handlmg by embeddm -• the relevant page server command element m a hyperimked group The page server activates the hyperlmk associated with the hyperimked group rather than executing the page server command A page server command element is hidden if its "hidden" attπbute is set A hidden command element does not have an mput zone on a page and so cannot be activated duectly by a user It can, however, be activated via a page server command embedded m a different page, if that page server command has its "on selected" attribute set 1.8 STANDARD FEATURES OF NETPAGES In the prefeπed foπn, each netpage is pπnted with the netpage logo at the bottom to mdicate 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 copy 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 advertismg page The default smgle-page copy function is handled directly by the relevant netpage page server Special copy functions are handled by linking the logo button to an application 1.9 USER H ELP SYSTEM In a preferred embodiment, the netpage pnnter has a smgle button labelled "Help" When pressed it elicits a smgle page of mformation, mcludmg • status of pπnter connection • status of pπnter consumables - 21 - • 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 pressing 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 duectory 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 Dependmg 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 "eπor" 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 mechamsms m the netpage svstem Although news is often used m 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 advertismg 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 mterest profile The advertismg 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 correspond 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 handlmg the aggregation and hence the formatting of news streams selected duectly by the reader, the server is able to place advertismg on pages over which it otherwise has no editonal control The subscnber builds a daily newspaper by selectmg one or more contnbutmg news publications, and creating a personalized version of each The resultmg daily editions are pnnted and bound together mto a smgle newspaper The vanous members of a household typically express theu 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 Tunes 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 - 22 - The reader can extend the daily newspaper by creating custom sections, each one drawing on any number of 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 (I e as a limit on its number of pages), and the desued proportion of advertismg, either qualitatively (e g high, normal, low, none), or numencally (1 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) m both short and long forms to support this preference An article may also be wntten (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 then 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, m pπonty order, subject to space constraints m the subscnbers' 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 for 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 effectively 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 mterest 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 unages 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 unpenal or metric, a local timezone and tune format, and a local currency, and whether the localization consist of in situ translation or annotation These preferences are deπved 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 accordmgly, and less mformation is accommodated on each page The language m which a news publication is published, and its correspondmg text encoding, is a property of the publication and not a preference expressed by the user However, the netpage system can be configured to provide automatic translation services m vanous guises 2.2 ADVERTISING LOCALIZATION AND TARGETING The personalization of the editonal content duectly affects the advertismg content, because advertismg is typically placed to exploit the editonal context Travel ads, for example, are more likely to appear m a travel section - 23 - 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 nght demographics Effective advertismg is placed on the basis of locality and demographics Locality determines proximity to particular services, retailers etc , and particular mterests and concerns associated with the local community and environment Demographics detemune general mterests and preoccupations as well as likely spending patterns A news publisher's most profitable product is advertismg "space", a multi-dunension-d entity determined by the publication's geographic coverage, the size of its readership, its readership demographics, and the page area available for advertismg In the netpage system, the netpage publication server computes the approximate multi-dimensional size of a publication's saleable advertismg space on a per-section basis, takmg mto account the publication's geographic coverage, the section's readership, the size of each reader's section edition, each reader's advertismg proportion, and each reader's demographic In compaπson with other media, the netpage system allows the advertismg 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 advertismg "slot" can be sold m varying proportions to several advertisers, with individual readers' pages randomly receiving the advertisement of one advertiser or another, overall preserving the proportion of space sold to each advertiser The netpage system allows advertismg to be linked directly to detailed product uiformation and onlme purchasing It therefore raises the lntπnsic value of the advertismg space Because personalization and localization are handled automatically by netpage publication servers, an advertismg aggregator can provide arbitranly 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 advertismg aggregators than to duectly capture advertismg Even though the advertismg aggregator is takmg a proportion of advertismg revenue, publishers may find the change profit-neutral because of the greater efficiency of aggregation The advertismg aggregator acts as an mtermediary 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 m the publication's traditional counterpart, because the publication's advertismg space is more complex While ignoring the full complexities of negotiations between advertisers, advertismg aggregators and publishers, the preferred form of the netpage system provides some automated support for these negotiations, mcludmg support for automated auctions of advertismg space Automation is particularly desuable for the placement of advertisements which generate small amounts of mcome, 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 Correspondmgly, 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 from the netpage ad server Accordmgly, a user may be provided with a netpages, which may more generally be referred to as a pπnted document with user mteractive elements, formatted in accordance with then 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 uiformation may be provided m the form of an advertismg brochure The manner m which the mteractive elements) are pnnted m the document and with which the sensing device is used to mteract with the element(s), to - 24 - uidicate 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 mformation, mcludmg • publication customizations • collaborative filtenng vectors • contact details • presentation preferences The customization of a publication is typically publication-specific, and so the customization uiformation 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 mamtauung a smgle collaborative filtenng vector mdependently of any particular publication, there are two reasons why it is more practical to mamtam 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 advertismg relies on the locality mdicated m the user's contact details, while the targeting of advertismg relies on personal uiformation such as date of birth, gender, mantal status, mcome, profession, education, or qualitative denvatives 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 uiformation, advertismg can be targeted on the basis of the demographic associated with the user's ZIP or ZTP+4 Code Each user, pen, pπnter, application provider and application is assigned its own umque identifier, and the netpage registration server mamtams the relationships between them, as shown m Figures 21, 22, 23 and 24 For registration purposes, a publisher is a special land of application provider, and a publication is a special land of application Each user 800 may be authonzed to use any number of pnnters 802, and each pπnter may allow any number of users to use it Each user has a smgle default pπnter (at 66), to which penodical publications are delivered by default, whilst pages prmted on demand are delivered to the pπnter through which the user is mteracting The server keeps track of which publishers a user has authonzed to pnnt to the user's default pnnter A publisher does not record the ID of any particular pnnter, but mstead resolves the ID when it is required When a user subscnbes 808 to a publication 807, the publisher 806 (I e application provider 803) is authoπzed to pπnt to a specified pnnter or the user's default pnnter This authorization can be revoked at any time by the user Each user may have several pens 801, but a pen is specific to a smgle user If a user is authorized to use a particular pπnter, 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 - 25 - server, via the DNS m the usual way A Web termmal 809 can be authoπzed to pnnt on a particular netpage pπnter, allowing Web pages and netpage documents encountered dunng Web browsmg to be convemently 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 pπnters Such mcome can mclude advertismg fees, click-through fees, e- commerce commissions, and transaction fees If the pπnter is owned by the user, then the user is the pπnter 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, any number of biometnc records 817, containing the user's encoded signature 818, fmgerpnnt 819 etc, a handwπtmg 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 "favoπtes" - 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 m Figure 41 2.3.3 History List The system mamtams 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 lays out the pages of each user's personalized publication on a section-by-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 algonthm exploits this The algonthm is configured to attempt to co-locate closely tied editonal and advertismg content, such as placmg ads for roofing matenal specifically withm the publication because of a special feature on do-it-yourself roofing repaus 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 closely achieve the user's stated section size preference The section size preference can, however, be matched on average over tune, allowing significant day-to-day vaπations 2.5 DOCUMENT FORMAT Once the document is laid out, it is encoded for efficient distπbution and persistent storage on the netpage network The primary efficiency mechanism is the separation of mformation specific to a smgle user's edition and mformation shared between multiple users' editions The specific mformation consists of the page layout The shared mformation consists of the objects to which the page layout refers, mcludmg images, graphics, and pieces of text A text object contams fully-formatted text represented m the Extensible Markup Language (XML) usmg 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 by the layout The text object contams embedded language codes to enable automatic translation, and embedded hyphenation hints to aid with paragraph formatting - 26 - An unage 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 seπes of placed image and graphic objects, linked textflow objects through which text objects flow, hyperlinks and mput fields as descnbed above, and watermark regions These layout objects are s-unmanzed m Table 3 The layout uses a compact format suitable for efficient distnbution 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 distributed, the netpage publication server allocates, with the help of the netpage ID server 12, a umque ID for 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 for 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 pomtcasts each user's layouts to that user's pnnter via the appropnate page server, and when the pomtcasting 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 Once a pπnter has received all the objects to which its page layouts refer, the pnnter re-creates the fully- populated layout and then rasteπzes and pπnts it Under normal circumstances, the pπnter 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 pπnter can therefore hold m excess of 100 such pages m its mtemal 64MB memory, allowing for temporary buffers etc The pnnter 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 - 27 - 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 pπnter' s 100-page internal storage capacity is exhausted However, if the printer'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 therefore 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 correspondmg shared objects Once a document is pnnted, 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 periodical However, smce there is no shared content, delivery is made directly to the requesting pπnter 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 pπnted page to present Web pages m a multi-column format, with a table of contents It can automatically mclude all Web pages duectly linked to the requested page The user can tune this behavior via a preference The netpage formatting server makes standard netpage behavior, mcludmg interactivity and persistence, available on any Internet document, no matter what its ongm 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 system also allows for delivery of books The information is formatted usmg an appropnate server and the book is then pπnted at a netpage pnnter 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 uiformation is preferably pπnted on demand at the pnnter following a request for same Havmg books available for pnntmg on the netpage system also means that users can obtam the latest bestsellers or rare "out-of-pπnt" (a soon-to-be-obsoleted term) editions on demand, pπnted m 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 handlmg Titles which have outlived then copynght penod can be available for free Other titles can be heavily discounted for netpage delivery, smce publishers avoid the costs of printing, inventory storage, and delivery Colourful children's books reproduce immaculately When they've been loved to death, they can be pπnted agam, and agam Children's coloπng-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 m storage and in transit, and to authenticate parties to a transaction There are two classes of cryptography in widespread use secret-key cryptography and public-key - 28 - cryptography The netpage network uses both classes of cryptography Secret-key cryptography, also referred to as symmetπc 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 Public-key cryptography, also referred to as asymmetric cryptography, uses two encryption keys The two keys are mathematically related m such a way that any message encrypted usmg one key can only be decrypted usmg the other key 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 usmg the pnvate key Thus two parties can securely exchange messages without first havmg 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 pnvate key with respect to that particular message by decrypting the encrypted hash usmg the public key and veπfying the hash against the message If the signature is appended to the message, then the recipient of the message can venfy both that the message is genuine and that it has not been altered m transit To make public-key cryptography work, there has to be a way to distribute public keys which prevents impersonation This is normally done usmg certificates and certificate authonties A certificate authonty is a trusted thud party which authenticates the connection between a public key and someone's identity The certificate authonty venfies the person's identity by examuung 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 genuine They just have to venfy that the certificate has mdeed been signed by the certificate authonty, whose public key is well-known In most transaction envnonments, public-key cryptography is only used to create digital signatures and to securely exchange secret session keys Secret-key cryptography is used for all other purposes In the following discussion, when reference is made to the secure tr-e. mission of information between a netpage pπnter and a server, what actually happens is that the pπnter obtains th 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 pan of umque identifiers at tune of manufacture which are stored m read-only memory m the pnnter 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 pnnter connects to the netpage network for the first time after installation, it creates a signature pubhc/pnvate key pan It transmits the secret ID and the public key securely to the netpage registration server The server compares the secret ID against the pπnter' s secret ID recorded m its database, and accepts the registration if the IDs match It then creates and signs a certificate containing the pπnter' 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 veπfy pnnter identity When a user subscnbes to a publication, a record is created in the netpage registration server database - 29 - authoπzmg the publisher to pπnt the publication to the user's default pnnter or a specified pnnter 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 pnvate signature key The page server venfies, via the registration database, that the publisher is authorized 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 pπnting authorizations to the database, so long as those requests are initiated via a pen registered to the pπnter 3.3 NETPAGE PEN SECURITY Each netpage pen is assigned a umque identifier at tune of manufacture which is stored m read-only memory m the pen and m the netpage registration server database The pen ID 61 umquely identifies the pen on the netpage network A netpage pen can "know" a number of netpage pπnters, 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 pπnter Once a pen and pnnter are registered, they regularly exchange session keys Whenever the pen transmits digital ink to the pπnter, the digital ink is always encrypted usmg the appropnate session key Digital ink is never transmitted m 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 by pen ID Both have a large but finite storage capacity for session keys, and will forget a session key on a least-recently-used basis if necessary When a pen comes withm range of a pπnter, the pen and pπnter discover whether they know each other If they don't know each other, then the pπnter detemunes 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 pnnter 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 tune it initiates the registration procedure In addition to its public ID, the pen contams a secret key-exchange key The key-exchange key is also recorded m the netpage registration server database at time of manufacture Dunng registration, the pen transmits its pen ID to the printer, and the pnnter transmits the pen ID to the netpage registration server The server generates a session key for the pnnter 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 mtemally, mdexed by the pen ID, and transmits the encrypted session key to the pen The pen stores the session key mtemally, mdexed by the pπnter ID Although a fake 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, 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 system supports the delivery of secure documents such as tickets and coupons The netpage pnnter mcludes a facility to pnnt watermarks, but will only do so on request from publishers who are suitably authonzed The publisher mdicates its authonty to pπnt watermarks in its certificate, which the pπnter is able to - 30 - authenticate The "watermark" pnntmg process uses an alternative dither matnx m specified "watermark" regions of the page. Back-to-back pages contam mirror-image watermark regions which comcide when pnnted The dither matnces used m odd and even pages' watermark regions are designed to produce an interference effect when the regions are viewed together, achieved by looking through the pnnted sheet The effect is similar to a watermark m that it is not visible when looking at only one side of the page, and is lost when the page is copied by normal means Pages of secure documents cannot be copied usmg the built-in 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 mclude the user's photograph which was captured when the user registered biometnc information with the netpage registration server, as descnbed in Section 2 When presented with a secure netpage document, the recipient can veπfy its authenticity by requesting its status m the usual way The umque 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 point-of-presentation document venfication Clearly neither the watermark nor the user's photograph are secure in a cryptographic sense They simply provide a significant obstacle to casual forgery Onlme 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 reliably 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 m 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 mdependent of the type of accounts bemg used In SET, cardholders and merchants register with a certificate authonty and are issued with certificates containing then 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 then 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 gateway SET has not yet been adopted widely, partly because cardholder maintenance of keys and certificates is considered burdensome Interim solutions which mamtam 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 - 31 - The netpage system uses biometncs to authenticate the user and authorize SET payments Because the system is pen-based, the biometnc used is the user's on-lme signature, consisting of time- varying pen position and pressure A fingerpπnt 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 biometπc, not the authorization aspects of the system The first step to bemg able to make SET payments is to register the user's biometnc with the netpage registration server This is done m a controlled envnonment, for example a bank, where the biometnc can be captured at the same tune 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 pπnter securely transmits the order uiformation, the pen ID and the biometnc data to the netpage registration server The server venfies the biometnc with 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 system mcludes a mechanism for micro-payments, to allow the user to be convemently charged for pnntmg low-cost documents on demand and for copymg 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 already 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 any 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 in 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 mput When mput 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-pnnted 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 mamtams an anonymous relationship between a user and an application via a umque alias ID 65, as shown m Figure 24 Whenever the user activates a hyperlmk tagged with the "registered" attribute, 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 mamtams state information mdexed by alias ID, and is able to retneve user-specific state information without knowledge of the global identity of the user The system also mamtams 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 information - 32 - To assist the system m routing product bar code (UPC) "hyperlink" activations, the system records a favoπte application on behalf of the user for any number of product types Each application is associated with an application provider, and the system mamtams an account on behalf of each application provider, to allow it to credit and debit the provider for click-through fees etc An application provider can be a publisher of penodical subscnbed content The system 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 preferred 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 Dublm Core metadata element set, which is designed to facilitate discovery of elecfromc resources Dublm Core metadata conforms to the World Wide Web Consortium (W3C) Resource Descπption Framework (RDF) A resource descnption may identify nghts holders 920 The netpage system automatically transfers copynght fees from users to πghts holders when users pπnt copynght content 5 COMMUNICATIONS PROTOCOLS A commumcations protocol defines an ordered exchange of messages between 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 m which the hoπzontal 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 lifelme of the entity Dunng the time an entity exists, the lifelme is shown as a dashed lme Dunng the time an entity is active, the lifelme 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 preferred embodiment of a subscnption delivery protocol is shown ir Fiaure 43 A large number of users may subscnbe to a penodical publication >ach user's edition may be laid out differently, but many users' editions will share common content such as text objects and image objects The subscnption delivery protocol therefore delivers document structures to mdividual pπnters via pomtcast, but delivers shared content objects via multicast The application (l 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 ID and alias ID to obtam from the registration server the correspondmg user ID 60, the user's selected pnnter ID 62 (which may be explicitly selected for the application, or may be the user's default pπnter), 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 ID and alias ID don't together identify a subscnption 808 The page server then allocates document and page mstance IDs and forwards the page descnptions, mcludmg page JDs 50, to the pnnter It mcludes the relevant set of multicast channel names for the pnnter 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 - 33 - the relevant page servers, it multicasts the vanous subsets of the shared objects on the previously selected multicast channels Both page servers and pπnters 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 pπnt the documents 5.2 HYPERLINK ACTIVATION PROTOCOL A preferred embodiment of a hyperlink activation protocol is shown m Figure 45 When a user clicks on a netpage with a netpage pen, the pen commumcates the click to the nearest netpage pnnter 601 The click identifies the page and a location on the page The pnnter already knows the ID 61 of the pen from the pen connection protocol The pnnter detemunes, via the DNS, the network address of the page server 10a handlmg the particular page ID 50 The address may already be m its cache if the user has recently mteracted with the same page The pπnter then forwards the pen ID, its own pπnter ID 62, the page ID and click location to the page server The page server loads the page descnption 5 identified by the page ID and detemunes 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 obtams the associated application ID 64 and link ID 54, and determines, via the DNS, the network address of the application server hosting the application 71 The page server uses the pen ID 61 to obtam the correspondmg user 3D 60 from the registration server 11, and then allocates a globally umque hyperlmk request ID 52 and builds a hyperlmk request 934 The hyperlink 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 ID 53, the hyperlink request ID, and the link 3D to the application The application produces a response document accordmg to application-specific logic, and obtams a document 3D 51 from an 3D server 12 It then sends the document to the page server 10b responsible for the document's newly allocated 3D, together with the requesting page server's ID and the hyperlmk request 3D The second page server sends the hyperlink request 3D and application ID to the first page server to obtam the corresponding user 3D and pπnter ID 62 The first page server rejects the request if the hyperlink request has expued or is for a different application The second page server allocates document mstance and page 3Ds 50, returns the newly allocated page IDs to the application, adds the complete document to its own database, and finally sends the page descnptions to the requesting pπnter The hyperlmk mstance may mclude a meaningful transaction 3D 55, m which case the first page server mcludes the transaction 3D 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, I e its "alias required" attribute is set, then the first page server sends both the pen ID 61 and the hyperlink's application 3D 64 to the registration server 11 to obtam not just the user ID correspondmg to the pen ID but also the alias ID 65 correspondmg to the application 3D and the user ID It mcludes the alias ID m 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 commumcates the stroke to the nearest netpage pπnter The stroke identifies the page and a path on the page The pnnter forwards the pen 3D 61, its own pnnter 3D 62, the page ID 50 and stroke path to the page server - 34 - 10 m the usual way The page server loads the page descπption 5 identified by the page ID and detemunes which mput element's zone 58, if any, the stroke mtersects Assummg 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 mactivity m the zone of the text field, the page server sends the pen ID 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 handwπting model 822 to mterpret the strokes as handwritten text Once it has converted the strokes to text, the registration server returns the text to the requesting page server The page server appends the text to the text value of the text field 5.4 SIGNATURE VERIFICATION PROTOCOL Assuming the mput 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 mactivity 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 ID 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 biometπc 818 to venfy the strokes as the user's signature Once it has venfied the signature, the registration server uses the application 3D 64 and user ID 60 to identify the user's application-specific pnvate signature key It then uses the key to generate a digital signature of the form data, and returns the digital signature to the requesting 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 mcludes the alias ID 65 of the correspondmg user This allows a smgle form to capture multiple users' signatures 5.5 FORM SUBMISSION PROTOCOL A prefeπed 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 hyperlink, the hyperlmk activation message sent by the page server 10 to the application 71 also contains the form ID 56 and the cuπent data content of the form If the form contams any signature fields, then the application venfies each one by extracting the alias 3D 65 associated with the correspondmg digital signature and obtaining the correspondmg certificate from the registration server 11 5.6 COMMISSION PAYMENT PROTOCOL A preferred embodiment of a commission payment protocol is shown m Figure 47 In an e-commerce envnonment, fees and commissions may be payable from an application provider to a publisher on click-throughs, transactions and sales Commissions on fees and commissions on commissions may also be payable from the publisher to the provider of the pπnter The hyperlink request ID 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 (I e publisher), and from the source application provider 70b to the pnnter provider 72 The target application receives the hvperlink request ID from the page server 10 when the hyperlmk is first activated, as descnbed m Section 5 2 When the target application needs to credit the source application provider, it sends the application provider credit to the ongmal page server together with the hyperlink request 3D The page server uses the hyperlink request ID to identify the source application, and sends the credit on to the relevant registration - 35 - server 11 together with the source application ID 64, its own server 3D 53, and the hyperlink request ID The registration server credits the correspondmg 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 oπgmal page server together with the hyperlink request ID The page server uses the hyperlink request ID to identify the pnnter, and sends the credit on to the relevant registration server together with the pnnter ID 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 pnnter 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 having 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 m order to enable the user to view the status of the LED mounted within the housmg 102 The cover 107 mcludes a mam part 109 which substantially surrounds the end 108 of the housmg 102 and a projecting portion 110 which projects back from the mam 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 surroundmg 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 mk cartndge replacement Also mounted within the cover 107 is a tn-color status LED l lό 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 of 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 mk pen cartndge 118 with nib 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 mk cartπdge 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 barrel 125 mcludes a cam 126 m the form of a slot withm the walls 181 of the cam barrel Cam followers 127 and 128 projecting from slider blocks 123 and 124 fit withm 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 114 The pen 101 has three states of operation By turning the top 105 through 90° steps, the three states are Stylus 120 mb 121 out, Ink cartndge 118 mb 119 out, and • Neither ink cartridge 118 nib 119 out nor stylus 120 mb 121 out A second flex PCB 129, is mounted on an electronics chassis 130 which sits withm the housmg 102 The second flex PCB 129 mounts an infrared LED 131 for providmg infrared 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 confrollmg operation of the pen 101 An optics block 135 (formed from moulded clear plastics) sits within the cover 107 and projects an infrared beam onto the surface and receives unages onto the image sensor 132 Power supply wnes 136 connect the components on the second flex PCB 129 to battery contacts 137 which - 36 - are mounted within the cam barrel 125 A termmal 138 connects to the battery contacts 137 and the cam barrel 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 118 is used for wnting, m order to enable a determmation of the force bemg applied to the surface by the pen mb 119 or stylus mb 121 The 3R photodiode 144 detects light from the IR 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 gnpping 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 -urranged to determine the position of its mb (stylus mb 121 or ink cartridge b 119) by imaging, m the infrared spectrum, an area of the surface m the vicinity of the mb It records the location data from the nearest location tag, and is arranged to calculate the distance of the mb 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 mb-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 security and packaged for 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 cncuitry mcludes a buffer arranged to store digital ink data for 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 m 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 IR lllummation LED 131, the 3R force sensor LED 143, and the force sensor photodiode 144 The pen controller chip 134 mcludes a confrollmg processor 145 Bv < 146 enables the exchange of data between components of the controller chip 134 Flash memory 147 and a 512 Kι DRAM 148 are also mcluded An analog-to-dtgital converter 149 is arranged to convert the analog signal from the force sensor photodiode 144 to a digital signal An image sensor mterface 152 mterfaces with the image sensor 132 A transceiver controller 153 and base band cucuit 154 are also mcluded to mterface with the RF chip 133 which mcludes an RF cuc t 155 and RF resonators and mductors 156 connected to the antenna 112 The confrollmg processor 145 captures and decodes location data from tags from the surface via the image sensor 132, momtors the force sensor photodiode 144, controls the LEDs 116, 131 and 143, and handles short-range radio commumcation via the radio transceiver 153 It is a medium-performance (~40MHz) general-purpose RISC processor The processor 145, digital transceiver components (transceiver controller 153 and baseband cucmt 154), unage sensor mterface 152, flash memory 147 and 512KB DRAM 148 are mtegrated m a smgle controller ASIC Analog RF components (RF cucuit 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 Elecfromc Corporation, and is descnbed m a paper by Itakura, K T Nobusada, N Okusenya, R Nagayoshi, and M Ozaki, "A 1mm 50k-Pιxel 3T CCD Image Sensor for Miniature Camera System", 3EEE Transactions on Elecfromc Devices, Volt 47, number 1, January 2000, which is incorporated herein by reference) with an IR filter - 37 - The controller ASIC 134 enters a quiescent state after a penod of mactivity when the pen 101 is not m contact with a surface It mcorporates a dedicated circuit 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 commumcates m the unlicensed 900MHz band normally used by cordless telephones, or alternatively m the unlicensed 2 4GHz mdustnal, scientific and medical (ISM) band, and uses frequency hoppmg and collision detection to provide mterference-free commumcation 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 pan of orthogonal accelerometers mounted m the normal plane of the pen 101 axis The accelerometers 190 are shown m Figures 9 and 10 m ghost outline 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 3D 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 ID of each location tag within the area of the mput element can duectly identify the mput element The acceleration measured by the accelerometers m each of the x and y dnections is mtegrated with respect to time to produce an instantaneous velocity and position Smce the starting position of the stroke is not known, only relative positions withm a stroke are calculated Although position integration accumulates errors m the sensed acceleration, accelerometers typically have high resolution, and the tune duration of a stroke, over which errors accumulate, is short 7. NETPAGE PRINTER DESCRIPTION 7.1 PRINTER MECHANICS The vertically-mounted netpage wallpπnter 601 is shown fully assembled m Figure 11 It pπnts netpages on Letter/A4 sized media using duplexed 8 1 /-" Memjet™ pnnt engmes 602 and 603, as shown in Figures 12 and 12a It uses a straight paper path with the paper 604 passmg through the duplexed pnnt engines 602 and 603 which pnnt both sides of a sheet simultaneously, m full color and with full bleed An mtegral bmdmg assembly 605 applies a stnp of glue along one edge of each pπnted sheet, allowing it to adhere to the previous sheet when pressed against it This creates a final bound document 618 which can range m thickness from one sheet to several hundred sheets The replaceable ink cartndge 627, shown in Figure 13 coupled with the duplexed pnnt engmes, has bladders or chambers for storing fixative, adhesive, and cyan, magenta, yellow, black and mfrared inks The cartridge also contams a micro au filter m a base molding The micro au filter mterfaces with an au pump 638 mside the pnnter via a hose 639 This provides filtered au to the pπntheads to prevent ingress of micro particles mto the Memjet™ prmtheads 350 which might otherwise clog the pnnthead nozzles By incorporating the au filter within the cartridge, the operational life of the filter is effectively linked to the life of the cartndge The ink cartndge is a fully recyclable product 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 duectly from the media tray past a paper sensor on the first pnnt engme 602 mto the duplexed Memjet™ pnnthead assembly The two Memjet™ pπnt engines 602 and 603 are mounted m an opposmg m-lme sequential configuration along the straight paper path The paper 604 is drawn mto the first pπnt engme 602 by mtegral, powered pick-up rollers 626 The position and size of the paper 604 is sensed and full bleed pnntmg commences Fixative is pπnted simultaneously to aid drying m the shortest possible tune - 38 - The paper exits the first Memjet™ pπnt engme 602 through a set of powered exit spike wheels (aligned along the straight paper path), which act against a rubberized roller These spike wheels contact the 'wet' pπnted surface and continue to feed the sheet 604 mto the second Memjet™ pnnt engme 603 Referring to Figures 12 and 12a, the paper 604 passes from the duplexed pnnt engmes 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 mterface 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 cartridge 627 This axle 679 connects to a glue wheel, which absorbs adhesive by capillary action through radial holes A molded housmg 682 surrounds the glue wheel, with an opening at the front Pivoting side moldmgs and sprung outer doors are attached to the metal bracket and lunge 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 penods 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 pπnter controller consists of a confrollmg processor 750, a factory-installed or field-installed network mterface module 625, a radio transceiver (transceiver controller 753, baseband cucmt 754, RF cucuit 755, and RF resonators and mductors 756), dual raster image processor (RIP) DSPs 757, duplexed pnnt engme controllers 760a and 760b, flash memory 658, and 64MB of DRAM 657, as illustrated m Figure 14 The confrollmg processor handles commumcation with the network 19 and with local wueless netpage pens 101, senses the help button 617, controls the user mterface LEDs 613-616, and feeds and synchronizes the 3UP DSPs 757 and pπnt engine controllers 760 It consists of a medium-performance general-purpose microprocessor The confrollmg processor 750 commumcates with the pπnt engme controllers 760 via a high-speed seπal bus 659 The RIP DSPs rastenze and compress page descnptions to the netpage pπnter' s compressed page format Each pnnt engine controller expands, dithers and prints page unages to its associated Memjet™ pπnthead 350 m real time (I e at over 30 pages per mmute) The duplexed pπnt engine controllers pnnt both sides of a sheet simultaneously The master pnnt engme controller 760a controls the paper transport and monitors mk usage m conjunction with the master QA chip 665 and the ink cartndge QA chip 761 The pπnter 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 main memory 657 at boot time The processor 750, DSPs 757, and digital transceiver components (transceiver controller 753 and baseband cucmt 754) are mtegrated m a smgle controller ASIC 656 Analog RF components (RF cucmt 755 and RF resonators and mductors 756) are provided m a separate RF chip 762 The network interface module 625 is separate, smce netpage pπnters allow the network connection to be factory-selected or field-selected Flash memory 658 and the 2x256Mbιt (64MB) DRAM 657 is also off-chip The prmt engme controllers 760 are provided m separate ASICs A vanety 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 include POTS modems, Hybnd Fiber-Coax (HFC) cable modems, ISDN modems, DSL modems, satellite transceivers, current and next- generation cellular telephone transceivers, and wueless local loop (WLL) transceivers Local mterfaces mclude IEEE 1284 (parallel port), lOBase-T and 100Base-T Ethernet. USB and USB 2 0, IEEE 1394 (Fuewue), and vanous - 39 - emerging 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 commumcates m the unlicensed 900MHz band normally used by cordless telephones, or alternatively m the unlicensed 24GHz industrial, scientific and medical (ISM) band, and uses frequency hoppmg and collision detection to provide mterference-free commumcation The pπnter 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 commumcation 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 RIP software on the DSPs 757 The DSPs 757 rastenze each page descnption 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 smce an arbitrary number of rastenzed pages can, m general, be stored m memory This strategy only leads to potentially poor DSP utilization when rastenzing short documents Watermark regions m 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 contams coded netpage tags at a density of about six per mch Each tag encodes the page ID, tag 3D, and control bits, and the data content of each tag is generated dunng rasterization and stored m the compressed page image The main processor 750 passes back-to-back page unages to the duplexed pnnt engme controllers 760 Each pnnt engme controller 760 stores the compressed page image m its local memory, and starts the page expansion and pnntmg pipeline Page expansion and pnntmg is pipelined because it is unpractical to store an entire 114MB bi-level CIvIYK+3R page image m memory 7.2.2 PRINT ENGINE CONTROLLER The page expansion and pπnting pipeline of the pnnt engme controller 760 consists of a high speed IEEE 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 lme 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 engme controller pipeline Once the page has finished pπnting, the page just loaded is pπnted while another page is loaded The first stage of the pipeline expands (at 763) the JPEG-compressed contone CMYK layer, expands (at 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 layer The resultant bi-level CMYK+IR dot data is buffered and formatted (at 767) for pnntmg on the Memjet™ pnnthead 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 interface 768 When several pnnt engme controllers 760 are used m unison, such as m a duplexed configuration, they are - 40 - synchronized via a shared lme sync signal 770 Only 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 rendering pipeline, configuring the pnnthead 350 via a low-speed seπal bus 773, and confrollmg the stepper motors 675, 676 In the 8 1 /." versions of the netpage pπnter, the two pπnt engmes each prints 30 Letter pages per minute along the long dimension of the page (11"), givmg a lme rate of 8 8 kHz at 1600 dpi In the 12" versions of the netpage pnnter, the two pπnt engmes each pπnts 45 Letter pages per mmute along the short d mension of the page (8 1 /-"), givmg a lme rate of 102 kHz These lme rates are well within the operatmg frequency of the Memjet™ pnnthead, which m the current design exceeds 30 kHz 8 NETPAGE SECURE DOCUMENTS Tickets, coupons and similar documents which are required to support validaion, venfication or cancellation can be pnnted as netpage documents A user can purchase a ticket for an event and have the ticket pπnted on a netpage pπnter Purchasing can be performed via a netpage purchasing application with the product of the purchasing transaction bemg a ticket pπnted on demand on the user's netpage pnnter When the ticket is presented to obtam the goods or services associated with it the receiver can venfy the ticket, to detemune both that it is a real ticket and that it has yet to be redeemed Other functions, such as ticket validation and cancellation, can also be enabled via active elements on the pπnted ticket In situations where there is no netpage pπnter or other connection to the netpage network, the pπnted ticket (or coupon) can function as a conventional pπnted ticket The recipient must rely upon visual mspection to determme its validity To assist m this process a netpage document can be pπnted with a difficult-to-forge watermark The netpage watermark is formed from infraction between specific dither matnces used to pnnt regions on the front and back sides of the pnnted sheet The watermark is visible only when looking through the sheet and is not visible if only a smgle side is viewed Netpage tickets may also mclude the user's photograph which is helpful m applications requiring user authentication yet with no access to the netpage network to automatically venfy titΛets The photo assists m provmg the ticket earner is m fact the ticket holder Certain types of ticketed events may requue such a level of authentication Automatic venfication of a netpage ticket is performed usmg a netpage pen or similar netpage sensmg device and some form of connection to the netpage network, I e usually a netpage pπnter although other methods of access are possible Actual ticket venfication is a function of a netpage-based ticketing application To venfy a ticket a suitably authoπzed application user activates a hyperlink element on the netpage ticket The Netpage system resolves this action to the appropnate operation m the ticketing application which causes it to venfy the ticket Ticket validity is checked and feedback provided accordmg to the ticket's status User feedback from the application may be provided m a vanety of ways One method is to have the user's netpage pen have a special mdicator that shows the status of the checked document Another method is to use an mdicator separate from the netpage network and controlled duectly by the ticketing application 8.1 APPLICATION DRAWING NOTATION An application user mterface flow is illustrated as a collection of documents linked by command arrows A command arrow mdicates that the target document is pnnted as a result of the user pressmg the correspondmg 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 pπnted Although multiple commands may label the same command arrow, they typically have different side-effects - 41 - In application terms, it is important to distinguish between netpage documents and netpage forms Documents contam pnnted 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 behaving like normal documents, also contam mput fields which can be filled m by the user They provide the system with a data mput mechanism It is also useful to distinguish between documents which contam genenc mfoimation and documents which contam information specific to a particular mteraction 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 forms encountered in pre-pnnted publications They may, of course, also be generated on-the-fly by a netpage pπnter m response to user requests User-specific documents and forms are normally generated on the fly by a netpage pnnter m response to user requests Figure 48 shows a genenc document 990, a genenc form 991, a user- specific document 992, and a user-specific form 993 Netpages which participate m a user mterface flow are further descnbed by abstract page layouts A page layout may contam vanous lands 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 mfoimation 995, mput fields 996, command buttons 997, and draggable commands 998 When a user mterface flow is broken up mto multiple diagrams, any document which is duplicated is shown with dashed outlines in all but the mam diagram which defines it 8.2 TICKETS Control elements such as a <veπfy ticket> hyperlink and other similar functions may be pnnted on the reverse side of the ticket as is commonly done with conventional ticketing mformation Such an approach allows the ticket to retain a conventional appearance which may be of benefit m a particular application Netpage tickets provide the normal facilities of netpages Pages may provide access to onlme services, for example services related m some way to the ticketed event, and other functions of the netpage system are available to ticket holders The ticket holder can use the ticket to easily obtain pnnted details, via a netpage pπnter, of the ticketed event One function that is usually not available with tickets or other so-called secure documents is that of duplication Normally netpages may be duplicated by activating the netpage logo element usually pπnted on the bottom of the page Documents that act as tickets may not be duplicated and the netpage logo mstead outputs a page descπbmg the event or possibly pnntmg a form that would allow more tickets to be purchased 8.3 COUPONS In a similar manner coupons can be pnnted on netpage pπnters Coupons are obtained via a different method than tickets, there bemg no need for a user-specific transaction, but m other respects behave m a similar manner Coupons, once distnbuted, may be redeemed to convey some benefit to the user and the receiver can automatically check theu validity usmg a netpage pen Coupons typically have a limited life span or other factors affecting then validity, for mstance some offers made via coupon are not legal m all locations, and this aspect is used by the coupon application to determine validity rather than the approach taken m a ticketing application Coupons often contam marks or then own identifiers to indicate the source of the coupon, e g , a particular magazine or hand-out This allows the issuer to judge the effectiveness of the coupon and to calculate the return on then mvestment Coupons pnnted by the netpage system allow for similar information to be determined automatically Coupons may be assigned different coupon identifiers accordmg to where, when or how they are published and these document identifiers recorded and tracked by the coupon application - 42 - User pnvacy is mamtamed due to the use of user alias identifiers 65 when commumcating with netpage applications so it is not possible for coupon applications to detemune more information than is provided by the application's use of coupon identifiers 8.4 TICKETING OBJECT MODEL Figure 50 shows a ticketing application class diagram The principal element m the model is the ticket 500 A ticket is pnnted as a netpage document that links to mformation m a ticketing database for a ticketed event 503 (the model presented here is for demonstrative purposes only, and the functions of such an application that do not concern netpage secure documents have been omitted for clarity) A ticket is assigned an identifier, unique withm the scope of a ticketed event, allowing it to be located m a ticketmg database The ticket identifier is used as a transaction identifier 55 m hyperlink element mstances 862 associated with the pnnted netpage ticket 506 Additionally a ticket has a status indicating if the ticket has been validated, redeemed, cancelled or is yet to be processed A ticket is associated with a ticketed event 503, a ticket vendor 504, and optionally a seat 501 A ticket is also associated with a ticketmg user 520, who is identified by an alias ID 65 and anonymously represents a netpage user 800 to the ticketing application Ticket details may change over time, and new tickets pπnted to reflect such changes, however a ticket's ticket identifier remains constant A suitably constructed ticketmg application may allow users to record all changes to the status of theu ticket and to access any of the "versions" of then ticket Tickets are purchased by performing a transaction with a ticket vendor There may be many ticket vendors and each may sell tickets to the same event A ticket is associated with a smgle ticket vendor only A ticketed event itself has an identifier along with information on the event such as its location and tune, and details on the seating allocation for the event Seating mformation compnses details such as the number of seats available and theu pncmg lnfoπnation, managed via seating groups 502 Seating groups may be deπved from a venue- specific plan or mav be event-specific The details are not important m relation to netpage ticket documents 8.5 TICKETING USER INTERFACE 8.5.1 Ticket Verification To venfy a ticket a suitably authonzed user of the ticketing application uses a netpage pen or similar sensmg device to select the <venfγ ticket> element on the ticket The <veπfy ticket element is a hyperlmk 844 which mvokes a ticket verification application function, passmg the ticket identifier by means of the hyperlmk mstance 's embedded transaction identifier 55 Given the ticket identifier, the ticketmg application performs a lookup on its database and alerts the user as to the status of the ticket The same method is used for venfymg a coupon The <venfy ticket> element is selected and an embedded coupon identifier is sent to the application The application checks the coupon's identifier agamst its database and applies the validation logic An indication as to the validity of the coupon is sent to the user The ticket venfication user mterface consists of a smgle hyperlink element located somewhere on the ticket As previously stated, some applications may pπnt this element on the reverse side of the ticket so as not to mterfere with the graphical presentation of the ticket itself Other applications may elect to incorporate the element mto theu mam mterface, or apply multiple meanings to the element depending upon who activates the element, e g a user who is not authoπzed to veπfy a ticket and who activates an element labelled <venfV ticket> is mstead presented with mformation concerning the status of the ticketed event An example ticket design and user mterface is shown m Figures 52 and 53 Figure 52 shows the front side 506a of the ticket, while Figure 53 shows the reverse side 506b of the ticket The <venfy ticket> hyperlink 512 is placed on the front of the ticket, and is comcident with event details 508, ticket details 509, and vendor details 510 In - 43 - the example there is no visual representation associated with the <venfy tιcket> hyperlink, 1 e it is effectively hidden If the correspondmg application function is programmed to ignore hyperlink activations from unauthorized users, then the function is effectively both visually and functionally hidden from unauthoπzed users, such as the ticket holder The front side of the ticket also has an <event rnfo> hyperlink 511 which requests up-to-date pπnted event mfoimation from the application The <veπfy ticket> hyperlink's zone is deliberately made large to allow venfication even if the ticket is severely damaged, and also to assist the person performing the venfication, smce they may need to quickly venfy a large number of tickets In the limit case the zone can cover the entire ticket surface 8.5.2 Ticket Validation and Cancellation Ticket validation and cancellation, operations which change the status of the ticket rather thanjust querying the ticket's status, can be supported via additional hyperlmk elements on the ticket As shown m Figure 53, the reverse side 506b of the ticket contams a <valιdate ticket> hyperlink 513 and a <cancel ticket> hyperlink 514 The <valιdate ticket instructs the ticketmg application to validate the ticket The <cancel ticket> hyperlink instructs the application to cancel the ticket If the user is an authoπzed ticket vendor representative, the ticket is validated or cancelled as appropnate, I e the ticket's status m the ticketing database is updated appropnately Validation may occur when the ticket holder fulfils some requirement, such as paying a fee Cancellation may occur when the ticket is redeemed or otherwise presented for entry to the ticketed event As shown m Figure 51, validation and cancellation may both elicit a new pπnted copy of the ticket (at 521) However, a checkmark, initial, or even a signature m the zone of the validation or cancellation hyperlink can leave a permanent record of the mteraction without requiring a new copy A checkmark field, drawing field or signature field can be embedded m a hyperimked group 866 for this purpose Coupons may also be cancelled m the same way when redeemed Coupons also typically expue with tune CONCLUSION The present mvention has been descnbed with reference to a preferred 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, differmg from those specifically descπbed, will also fall within the spurt and scope of the present mvention Accordmgly, it will be understood that the mvention is not intended to be limited to the specific embodiments descπbed m the present specification, mcludmg documents incorporated by cross-reference as appropnate The scope of the mvention is only limited by the attached claims

Claims: - 44 - CLAIMS 1 A method for providmg secure documentation, mcludmg the steps of providmg a secure document havmg pnnted information and coded data thereon, the coded data mcludmg a umque identifier mdicative of the secure document, recording, m a computer system, a correspondence between the secure document and validity status and/or authenticity mformation relating to the document, and providmg a sensmg device adapted to sense said coded data on the secure document, the sensmg device bemg further adapted for commumcation with said computer system, whereby the validity status and/or authenticity of said document can be determined by sensmg said coded data to obtam the secure document umque identifier and communicating with the computer system to detemune the validity status and or authenticity information coπesponding thereto 2 The method of claim 1 , wherem the secure document mcludes first and second pπnted patterns on opposed sides of a sheet matenal of the secure document, the first and second pnnted patterns forming a watermark pattern when viewed through the sheet matenal 3 The method of claim 1 or 2, wherem the coded data is pnnted on the secure document so as to be substantially invisible m the visible spectrum The method of any of claims 1 to 3, wherem the secure document is pπnted on demand 5 The method of claim 4, wherem the secure document is pπnted on demand m response to a request from a user through said computer system, and wherem the pπnted information mcludes a photographic representation of the requesting user 6 The method of any precedmg claim, wherem the secure document is produced as part of an electronic commerce transaction 7 The method of claim 1 , wherem the secure document is a ticket or coupon 8 The method of claim 7, wherem the validity status and/or authenticity mformation mcludes an indication of whether the ticket or coupon has been canceled by its issuer 9 A method of issuing secure documentation, such as tickets or coupons, mcludmg the steps of producmg a secure document havmg pnnted mfoimation and coded data thereon, the coded data mcludmg a umque identifier mdicative of the secure document, recording, m a computer system, a correspondence between the secure document and validity status and/or authenticity information relating to the document, and providmg a sensmg device adapted to sense said coded data on the secure document, the sensmg device bemg further adapted for commumcation with said computer system, whereby the validity status and/or authenticity of said document can be deterπuned by sensmg said coded data to obtam the secure document umque identifier and - 45 - commumcating with the computer system to determine the validity status and/or authenticity uiformation corresponding thereto, wherem the secure document is produced on demand m response to a request from a user to an issuer by way of said computer system, and wherem the secure document is produced at the user's premises 10 The method of claim 9, wherem the secure document mcludes first and second pnnted patterns on opposed sides of a sheet matenal of the secure document, the first and second pnnted pattems formmg a watermark pattern when viewed through the sheet matenal 11 The method of claim 9 or 10, wherem the coded data is pnnted on the secure document so as to be substantially invisible m the visible spectrum 12 The method of claim 9, wherem the pnnted mformation mcludes a photographic representation of the requesting user 13 The method of any one of claims 9 to 12, wherem the secure document is produced as part of an elecfromc commerce transaction 14 The method of claim 9, wherem the validity status and/or authenticity uiformation mcludes an indication of whether the ticket or coupon has been cancelled by its issuer 15 A secure documentation system mcludmg at least one termmal device adapted to produce a secure document havmg pnnted information and coded data thereon, the coded data mcludmg a umque identifier mdicative of the secure document, a computer system coupled to commumcate with the at least one terminal device and having a stored correspondence between the secure document and validity status and/or authenticity information relating to the document, and at least one sensmg device adapted to sense said coded data on the secure document, the sensing device bemg further adapted for commumcation with said computer system to obtam the stored validity status and/or authenticity mformation correspondmg to the secure document 16 The system of claim 15, wherem the termmal device mcludes a pnnter for pnntmg the pπnted mformation and the coded data 17 The system of claim 16, wherem the terminal device is controllable by a user to produce a secure document on demand, and wherem the coded data is supplied from an issuer through said computer system to the termmal device 18 The system of claim 17, mcludmg a secure document produced by said termmal device 19 The system of claim 18, wherem the secure document includes first and second pnnted patterns on opposed sides of a sheet matenal of the secure document, the first and second pπnted pattems forming a watermark pattern when viewed through the sheet matenal - 46 - 20 The system of any one of claims 15 to 19, wherem the coded data is pπnted on the secure document so as to be substantially invisible m the visible spectrum 21 The system of claim 16, wherem the secure document is pπnted on demand m response to a request from a user through said computer system, and wherem the pπnted information mcludes a photographic representation of the requesting user 22 The system of claim 18, wherem the secure document is produced as part of an elecfromc commerce transaction 23 The system of any one of claims 15 to 22, wherem the secure document is a ticket or coupon 24 The system of claim 23, wherem the validity status and or authenticity uiformation mcludes an mdication of whether the ticket or coupon has been canceled by its issuer

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: G06F7
IPC codes: B41J2, B41J5, B41J13, B41J21, B41J29, B42C9, B42C19, B42D15, B65H29, B65H37, G06F3, G06F13, G06F17, G06F21, G06K9, G06K17, G06K19, G06Q10, G06Q30, G06Q50, G06T1, G06T11, G08C17, H04L9, H04N1