Patent Publication Number: US-2005141542-A1

Title: Personnalization module for interactive digital television system

Description:
The present invention relates to an interactive digital television system comprising a broadcast operator adapted to send towards a plurality of subscriber units a downstream digital broadcast stream selected amongst a plurality of broadcast signals received from interactive digital television providers, and an interaction return channel operator adapted to provide interactivity between said plurality of subscriber units and said interactive digital television provider by means of bi-directional interaction return channels.  
      Such an interactive Digital TeleVision iDTV system, as shown at  FIG. 1 , is generally known in the art. The iDTV system contains an interactive Digital TeleVision provider ITVP, hereafter also called iDTV provider, and adapted to send a downstream digital broadcast stream BS, containing a combination of a digital video signal and program logic, to the broadcast operator BO. The broadcast operator broadcasts the digital stream BS to the subscriber units, e.g. SB. At each subscriber unit, the stream BS is decomposed into a video signal and program logic. The known interactive Digital Television system iDTV provides interactivity through the bi-directional interaction return channel IC via the return channel operator RCO. As a result, the following applications can be supplied: online voting, moderated (broadcasted) message boards, switch camera &amp; viewpoint, transpositions of internet services like e-mail, (AOL) instant messaging on TV broadcasts, . . . .  
      However, the known iDTV system doesn&#39;t offer integrated support for small user groups, user-presence indication nor the possibility of modifying or injecting content, e.g. personal content by the user of a subscriber unit SB. Currently each user or viewer of a broadcast stream has to take individually action to switch broadcast channel or to get any other kind of information, e.g. from another user. There is no support for advised, forced or synchronized switching of broadcast channels or receiving additional information. At most, the known system transposes Internet technologies, like instant messaging, to iDTV.  
      An object of the present invention is to provide an interactive digital television system of the above known type but which is adapted to integrate support for small user groups, to support user-presence indications and to allow for injecting personal content by a user and/or channel switching control.  
      According to the invention, this object is achieved due to the fact that said interactive digital television system further comprises a personalization module coupled to said bi-directional interaction return channels and adapted to allow intercommunication between subscriber units of said plurality.  
      In this way, the users of the subscriber units are allowed to communicate and exchange information with each other through the personalization module. In other words, the user of a subscriber unit can escape the limitations of the current linear TV programs and is transformed from a pure spectator into a producer and director of a collective or individual iDTV experience.  
      Another characterizing embodiment of the present invention is that said television system further comprises a community support module adapted to receive and to handle information about said subscriber units and to setup and maintain user groups constituted by subscriber units of said plurality.  
      The community support module knows about the users, user-groups and privacy preferences, this module can add or delete members or buddies to user groups and also setup and modify user groups based on implicit or on explicit information. Owing to this community support module, the community of users can be managed by the end-users themselves: they can add new buddy&#39;s, etc. and control the accesses. Users matching predetermined characteristic can also be automatically integrated in a particular user group, as it will become clear later.  
      In a preferred characterizing embodiment of the present invention, said community support module is comprised in said personalization module.  
      There is however no need for the community support module to be included in the personalization module for collecting the preferences of the users of the subscriber units.  
      Also another characterizing embodiment of the present invention is that said personalization module further comprises a presence module adapted to handle information about the status of said subscriber units and their links to other telecommunication facilities.  
      The presence module contains knowledge about presence of users on the subscriber units, about what the users are doing, and about the existing links, e.g. to Intelligent Networks, Instant Messaging systems or the like. The presence module may also contain technical information concerning the subscriber units.  
      Still another characterizing embodiment of the present invention is that said personalization module further comprises a terminal capability module adapted to receive information from said community support module and from said presence module and to control the operation of a content-reflector and forking module also comprised in said personalization module.  
      This terminal capability module will advice the content-reflector and forking module of the possibility, modalities and necessary transformations for sending control or data signals to the subscriber units. The known iDTV architectures do not allow other actors, as for instance the interaction return channel operator, to take up responsibility in providing iDTV functions. This can however be done, for instance by a user, through the operation of the terminal capability module and the content-reflector and forking module.  
      Owing to the personalization module, the end-user is empower to actively contribute to an iDTV experience by sharing multimedia content, such as movies, real-time video streams, voice, text, pictures, messaging, with a small group of buddies while collectively experiencing an iDTV application. The shared content may be personal content of a user or content broadcasted by the iDTV provider. A user may, for instance, be invited (or forced) to join the “swarming” of other users to switch to another broadcast channel. The terminal capability module advises this “swarm” of users of a same group, based on, e.g., common interest or users with a same profile.  
      The present invention is further also characterized in that said content-reflector and forking module is adapted to reflect to at least one subscriber unit of a particular user group, signals received from another subscriber unit belonging to said particular user group. The signals reflected by said content-reflector and forking module are either data signals or control signals.  
      The content-reflector and forking module receives data or control signals from a user, generally via other modules of the television system. If the received signals are data, the content-reflector and forking module reflects and duplicates (forks) these data signals to some or all members of a user group that are participating to a same iDTV experience. In other words, the content-reflector and forking module then allows “content injection” from a particular user to other users. If the received signal is a control signal, the content-reflector and forking module forwards the control to some or all members of a user group to recommend, to request or to force them to switch from broadcast channel. Anyway, this new embodiment empowers the users to personalize the interactive part of the iDTV experience, resulting in a higher perceived added-value.  
      Also in a preferred characterizing embodiment of the present invention, said presence module (L 4 ) is adapted to receive from said one subscriber unit (SB 2 , SB 3 ) instructions indicating whether said one subscriber unit (SB 2 , SB 3 ) wants to receive said signals unconditionally or only according to predetermined conditions.  
      In case the receiving users have decided to receive unconditionally the signals, these users of the group will all watching the same multimedia content or will all switch collectively to another channel. In case of predetermined conditions are set, the collective operation is subjected e.g. to a vote with a majority decision.  
      The present invention thus enables a user to join a “swarming” of users zapping across the broadcast channels. The system advises the receiving user on which “swarm of similar users” to join, based on for example common interests or profiles.  
      Also another characterizing embodiment of the present invention is that said interactive digital television system further comprises a broadcast data collector module (L 6 ) adapted to receive broadcasting information from said interactive digital television providers (ITVP), and that said personalization module (PM) further comprises a terminal capability module (L 5 ) adapted to receive information from said community support module (L 3 ), from said presence module (L 4 ), and from said broadcast data collector module (L 6 ), and to generate thereby channel selection signals.  
      Another advantage of the possibility to supervise the content injection, presence, buddy list, . . . switching control functions, is that the iDTV providers can also contribute by offering not only their core expertise: transport and enhanced communication services (presence, buddy list, personalization, billing, . . . ), but also suitable data broadcasting at appropriate time schedules.  
      Again in a preferred characterizing embodiment of the present invention, each subscriber unit (SB: SB 1 -SB 3 ) of said plurality comprises a set-top box (STB: STB 1 -STB 3 ), and said terminal capability module (L 5 ) is adapted to transmit said channel selection signals to the a set-top boxes of subscriber units (SB: SB 1 -SB 3 ) belonging to a same predetermined user group.  
      In this way, the above decision for a user to join a “swarming” of users zapping across the broadcast channels or receiving the same multimedia data may be taken by the user at the level of his set-top box rather than providing conditional instructions to the presence module as mentioned above.  
      Another characterizing embodiment of the present invention is that each subscriber unit of said plurality comprises a set-top box coupled to a server-side logic of said interactive digital television provider via said personalization module, and that said personalization module comprises an application logic proxy adapted to interpret signals sent over said interaction return channel between said set-top box and said server-side logic in order to forward selected ones of said signals to other parts of said interactive digital television system.  
      The application logic proxy is a front-end for the server-side logic of the iDTV provider. This proxy extracts and filters-out signals that may be needed, e.g., to allow users of the subscriber units to communicate with each other or to control their channel switching, while it can also forward signals from the subscriber units to the server-side logic, and vice versa.  
      Also another characterizing embodiment of the present invention is that said interaction return channel is a broadband Digital Subscriber Line, e.g. ADSL.  
      Further characterizing embodiments of the present interactive Digital TeleVision system iDTV are mentioned in the appended claims.  
      It is to be noticed that the term ‘comprising’, used in the claims, should not be interpreted as being restricted to the means listed thereafter. Thus, the scope of the expression ‘a device comprising means A and B’ should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.  
      Similarly, it is to be noticed that the term ‘coupled’, also used in the claims, should not be interpreted as being restricted to direct connections only. Thus, the scope of the expression ‘a device A coupled to a device B’ should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. 
    
    
      The above and other objects and features of the invention will become more apparent and the invention itself will be best understood by referring to the following description of an embodiment taken in conjunction with the accompanying drawings wherein:  
       FIG. 1  shows an interactive Digital TeleVision [iDTV] system as known from the prior art;  
       FIG. 2  represents an interactive Digital TeleVision [iDTV] system according to the invention with a personalization module (PM) in the return channel operator (RCO);  
       FIG. 3  represents a variant of the interactive Digital TeleVision [iDTV] system of  FIG. 2  with the personalization module (PM) in the interactive Digital TeleVision [iDTV] provider; and  
       FIG. 4  shows an example of content injection in the interactive Digital TeleVision [iDTV] system of  FIG. 3 . 
    
    
      The interactive Digital TeleVision system iDTV shown at  FIG. 1  is already known in the art. It comprises an interactive Digital TeleVision provider ITVP, hereafter also called iDTV provider, adapted to send a downstream digital broadcast stream BS to a broadcast operator BO. The digital broadcast stream BS contains a combination of a digital video signal and program logic. The broadcast operator BO broadcasts the digital stream to subscriber units, such as SB, either by satellite, cable, terrestrial broadcasting or over a broadband Internet infrastructure (possibly Internet Protocol IP) like ADSL, VDSL, . . . , i.e. Digital Subscriber Lines [DSL]. Each subscriber unit SB has a digital Set-Top Box STB that decomposes the stream BS into the video signal and the program logic. The program logic is executed on the set-top box and allows the user of a subscriber unit to interact. The combination of the video stream and graphical elements of the user consuming (interacting with) the program logic is then sent to the television set of the subscriber unit for visualization. It is to be noted that the subscriber unit may comprise the set-top box, a television set TV, a Personal Computer PC, a webcam, and/or any other multimedia device.  
      The interactive Digital Television system iDTV provides interactivity by means of a bi-directional interaction return channel IC. This interaction return channel IC, provided by an interaction return channel operator RCO, can be narrowband dial-up, broadband DSL, leased-line, wireless, Internet Protocol IP, non-IP, . . . . The interaction return channel operator RCO is transparent for the bi-directional interaction return channel IC; the interaction return channel operator RCO only provides transport and is coupled between the iDTV provider ITVP and the subscriber units.  
      The interaction return channel IC is terminated at the iDTV provider ITVP by a server-side logic L 1  that is adapted to interpret the upstream signals sent by the set-top box STB over the interaction return channel IC. This network-side counterpart L 1  of the program logic that is executing on the set-top box is able to influence both the video and the logic component of the downstream broadcast BS and can also send information back to the user over the unicast part of the interaction return channel IC. The server-side counterpart L 1  of the program or application logic takes care of interaction with the user of a subscriber unit and a video-mixer at the iDTV provider.  
      It is to be noted that the digital broadcast stream BS and the bidirectional interaction return channel IC can be transmitted over a same link, e.g. VDSL, or a combination of different links, e.g. Satellite for the digital broadcast stream BS and ADSL for the interaction return channel IC.  
      Additionally to the above-mentioned items, the interactive Digital TeleVision system iDTV of the present invention comprises a personalization module PM as shown at  FIG. 2 . The personalization module PM coupled to the bi-directional interaction return channel IC and is adapted to allow intercommunication between subscriber units SB, such as SB 1 , SB 2  and SB 3 . PM may be located at the return channel operator RCO (as shown at  FIG. 2 ), at the iDTV provider ITVP (as shown at  FIG. 3 ), at the iDTV broadcast operator BO or at a combination of these.  
      As will be explained below, implicit and/or explicit groups of users are created. Owing to different modules possibly but not obligatory located in the personalization module PM, a user of a group may send control or data signals to the other users of the group. Data signals may be multimedia data to ear and/or to display, and control signals may be recommendations to all the users of a group for switching to another broadcasted channel.  
      To achieve these facilities, the personalization module PM comprises some or all the following modules: 
          an application logic proxy L 1 ′,     a content-reflector and forking module L 2 ,     a community support module L 3 ,     a presence module L 4 ,     a terminal capability module L 5 , and     a broadcast data collector module L 6  
 
 preferably interconnected through a routing/forwarding layer or link RFL that distributes and forwards signals arriving/leaving over the interaction return channels IC to/from the modules L′ 1 -L 6 . 
       

      The application logic proxy L 1 ′ is a front-end for the known application logic L 1  that stays under the responsibility of the iDTV provider. The proxy L 1 ′ extracts, and possibly filters-out, the signals that are needed by the modules L 1 -L 4  and forwards unrelated signals, like for example a pan/tilt signal for a ITVP camera.  
      The community support module L 3  knows about users, user-groups and privacy preferences, this module may be (partly) managed by the end-users, they can add or delete members or buddies to user groups and also setup new user groups. The community support module L 3  is in fact a user profiles and events collector and profiler that collects relevant information and events (actions) provided by the user. These comprise keywords, preferences, interests, history of viewed broadcasts, summary of shared content, . . . . The module L 3  can construct profiles from analyzing these data and relate these profiles to groups of users having similar characteristics and maintains so explicit or implicit groups. Explicit groups are groups of users managed by the end users themselves. The so-called buddy list is an example of such a user-managed group. Implicit groups result out of a profile matching with some set of rules applied. A user profile can have real-time properties, for example with respect to his zapping behavior. By “zapping” is meant connecting to “content”, i.e. to select a broadcast channel, to select a stream, to connect to a content network, etc. By extension, a user can also “zap” to “personal broadcast channels”, i.e. connect to data made available by another user, the content source then comprises personal broadcast channels, i.e. dynamic content sources offered by individual peer users.  
      It is to be noted that a user can belong to a set of possibly mixed implicit or explicit communities and can be part of multiple user groups.  
      The community support module L 3  needs to be coupled, at least periodically, to the user in order to collect information thereof. However, L 3  is not obligatory located in the personalization module PM.  
      The presence module L 4  contains the knowledge about presence of all iDTV users based on information of their set-top box, such as: 
          is the user watching TV?    which channel?    is he linked to Intelligent Networks?    are Instant Messaging systems available?    does he wants to join the “swarming” of other users to switch to another broadcast channel, if he is invited (or forced)?    under what conditions does he wants to join: after majority voting, unconditionally, else . . . ?       

      The switch request to another content (broadcasted channel or personal data provided by a user) can result into anything between a forced switch where the user&#39;s channel is changed without any interaction by the end user himself, or an on-screen switch proposal. Somewhere in between, the switch request can require that first a consultation/negotiation phase with the user(s). Several decision rules for voting can be selected: unanimous where everyone has veto right, majority where at least half of the people agree, etc.  
      In other words, a zap request within a community can be one of the following: 
          zap recommendation: the user is presented a recommendation to zap to a specific channel. On acknowledgement he is switched towards the proposed content;     zap request with voting module: the whole of the community is proposed to move to another channel. All of the members can vote for the move. The presence module L 4  then acts as a zapper voting module that handles the voting and depending on the result, the community will connect to the proposed channel. This voting can be realized according to different voting strategies: by veto, by consensus, by majority, etc.; and     auto-zap, also called follow mode or slave mode: the user is “following” the zap behavior of another individual or of a community or the zap proposals by the zap recommendation engine.        

      It is to be noted that the channel switching also applies to the case where the set-top-box is the ‘channel’ selector, in the user&#39;s house.  
      The terminal capability module L 5  receives information from the community support module L 3  and from the presence module L 4 . L 5  is an engine that analyses the user profile (possibly including real-time properties) and decides what to do with the content currently offered by the different content providers.  
      The terminal capability module L 5  is further coupled to a broadcast data collector module L 6  which receives broadcasting information from the interactive digital television providers ITVP. In more detail, L 6  is a broadcast (meta-) data collector module also called channel management module that collects relevant information about the broadcast. This comprises keywords, subject, category, director, location, time-stamp, weather conditions, producer, actors, summary, . . . . This broadcast information can originate either from the broadcaster, a broadcast-stream processor extracting meta-information embedded in the broadcast video-stream, or even from a third party (multimedia encyclopedia). Owing to the broadcast data collector module L 6 , the terminal capability module L 5  is aware about the content currently available on the content network, broadcast channels, etc and can advise about a “swarm” of users of a same group, based on, e.g., common interest or users with a same profile.  
      In co-operation with the community module L 3 , the presence module L 4  and the broadcast data collector module L 6 , from which it receives information, the terminal capability module L 5  controls the content-reflector and forking module L 2 . The latter module L 2  receives, reflects and duplicates (forks) streams of personal or broadcast content from a user or from the television providers ITVP to all or part of online members of a community that are participating to a same iDTV experience. As already mentioned, data content may be movies, real-time audio/video streams, voice, text, pictures, messaging, data, meta-data, . . . , whilst control content may be recommendations to zap.  
      The content-reflector and forking module L 2  may thus be seen as a content switcher or a zapper execution engine that executes—triggered by the rules engine L 5 , itself controlled by L 3 , L 4  and L 6 —the switch to a (broadcast, personal, etc.) predetermined channel or personal data.  
      In co-operation, the community module L 3 , the presence module L 4 , the broadcast data collector module L 6  and the terminal capability module L 5 : 
          match broadcast-content&#39;s (meta-) data and user profiles;     match user profiles with profiles of user-population;     apply a rule-set on broadcast content; and     apply a rule-set on user and community events &amp; properties.        

      The community defines and manages the access roles to the rule set executed (or to be executed) by the assigned rules engine to the community. The rule set can be activated and modified (e.g. by a designated role in the community). Rules can applied on several elements like properties of the members of the community, on properties of their interest, on properties of the content broadcasted via the channels or categories, on properties of broadcaster agenda information, etc.  
      It is further to be noted that the modules L 3  and L 4  can work in a several modes: they can receive and store all the data from the different sources, they can lookup the required data when needed directly from the sources, the Internet, a peer-to-peer network, etc.  
      In an example to illustrate the operation of the present interactive digital television system iDTV, and referring to  FIG. 2 , a content stream from the subscriber unit SB 1  arrives over an interaction return channel IC 1  at the content reflector and forking module L 2  of the personalization module PM. This stream is forked into two content streams send to two buddies SB 2  and SB 3  using interaction return channels IC 2  and IC 3  respectively. The application logic on the set-top boxes STB 1 -STB 3  adds this content to the displayed stream BS from the broadcast operator BO.  
      As already mentioned, the scope of users that (can) receive the content that is injected by a user, e.g. SB 1 , is determined by the membership of a community combined with the preference of these users. A user can for example also select a subset of a community for certain content injections.  
      It is to be noted that technically the broadcast stream BS could also be used to convey a limited number of “private” streams.  
      It is also to be noted that a possible embodiment of the reflector could limit itself to distributing the knowledge about the connectivity of STB&#39;s buddies, members of a particular group, to all STB&#39;s such that the actual distribution of the content can be done by known multicast or peer-to-peer techniques, for instance by means of Internet Protocol IP.  
      The interaction return channel IC as well as the broadcast channel BS may not have enough capacity to support an application. The bandwidth may depend on the location and operator used by one of the buddies. Therefore, a terminal capability module L 5 , has been added as extension to the iDTV architecture: This module L 5  will advice module L 2  of the possibility, modalities and necessary transformations for sending a stream of content to a set-top box, e.g. can the set-top box accept incoming streams and if yes, at what rate? 
      It is to be noted that this capability information and function will typically reside at the broadcast operator BO or at the interaction return channel operator RCO. The interactive digital television provider ITVP will not take care about this problem.  
      It is also to be noted that partial scenarios in which only a subset of the modules L 1 -L 6  are involved are also possible. This means that all the modules L 1  to L 6  don&#39;t need to be simultaneously present in the personalization module PM.  
      In a variant embodiment of the present interactive digital television system iDTV, shown at  FIG. 3 , the modules L 1 -L 6  are located at the iDTV provider ITVP rather than at the return channel operator RCO as described above. In other possible variants, these modules L 1 -L 6  may also be located at the iDTV broadcast operator BO or spread over these parts RCO, ITVP and BO. Also different actors can take up the roles of RCO, ITVP and BO or a specific party can take up several roles. For example, a same cable-company can take up the roles of both the iDTV broadcast operator BO and the interaction return channel operator RCO.  
      As an example, in the interactive digital television system iDTV, shown at  FIG. 4 , a personal content is injected. This content may be originated from the set-top box STB 1  of the subscriber unit SB 1 . It is then for instance a video fragment that was recorded earlier on a hard disk of the set-top box STB 1 , a video stream from an attached camera, an audio stream from an attached microphone, a text chat, . . . transmitted via the interaction return channels IC 1a . It may also come from a Personal Computer PC providing views of a web cam or movies, a picture, sound, music, data from its hard disk, and transmitted via the interaction return channels IC 1b ; or it may transmitted via the interaction return channels IC 1c  and come from an external storage server ES coupled to the network and containing either personal content of the user or third party content to which the user gives a URL.  
      When the user of the subscriber unit SB 1 , hereafter called user SB 1 , switches-on his TV, he sees that some of his friends, users SB 2  and SB 3 , are watching a sports event. User SB 1  then joins the football channel and uses iDTV on his set-top box STB 1  for on-screen chatting with his group of friends SB 2  and SB 3 , shielded from the other viewers of the broadcast. While chatting, user SB 1  wants to share an interesting movie-clip that shows a sportsman doing an impressive performance at an earlier event. The movie-clip of user SB 1  streams from the hard disk of his set-top box STB 1  over the interaction return channel IC 1a  to the media reflector module L 2 . This module L 2  duplicates the stream and sends it to the set-top boxes STB 2  and STB 3  of the online friends SB 2  and SB 3  only. To this end, the media reflector module L 2  co-operates with the community module L 3  and the presence module L 4 , all under control of the terminal capability module L 5 . Alternatively, the movie-clip, showing the sportsman doing the performance at an earlier event, could also originate from the PC of user SB 1  or from a file from the external server ES to which user SB 1  gives a reference, for example under the form of a URL.  
      In another example of the application, the user of the subscriber unit SB 2  starts watching an educational movie for a school-assignment. He notices that some friends have already switched to the school-TV channel. While watching the educational movie, this sub-group of users, e.g. students, may video-chatting on-screen using iDTV. In the background, the modules L 1 -L 5  are doing the video-chat communication functionalities for them.  
      The iDTV director and producer do not have to bother that the iDTV provider has to provide the infrastructure for modules L 1 -L 6 . They can put placeholders for these functions (user-groups, buddies, presence, content forking and forwarding, . . . ) in their programs that will look for the proper instantiations of these functions. A suitable mechanism for this can be found in known web-services technology. The advantage of this possibility to delegate these functions is that the iDTV provider can focus on his core business: create and broadcast iDTV programs. Moreover, the iDTV broadcast operators, e.g. cable companies, and iDTV interaction return channel operators, e.g. telecom operator providing ADSL, can also contribute, and even make profit, by offering their core expertise: transport and enhance communication services, i.e. presence, buddy-list, personalization, billing, . . . .  
      Also in another example of the application, a group of users can initiate a switch of TV channel as a result of a discussion via communication over a separated channel (voice, video, VIP, etc.). The users of the group are for example all watching a tennis match. However, this match is getting pretty boring as it is becoming extremely clear that a certain player will win. One of the users notices that a specific episode of “XYZ” is going to start on another channel. A switch will be proposed to all the other members of the group and these members can follow the zapping to the other channel.  
      Users interested in the TV series “ZYX” can for instance start a community. Using the broadcast data collector module L 6 , the assigned rules engines will scan all channels, broadcast programs, and proposes an agenda for the evening or the upcoming days. On the appropriate time the channel manager will recommend a switch for the online members.  
      An advantage of the proposed interactive digital television system is that television spectators can follow each other in their interest and preferences. For example watching television together becomes a more interesting and memorable experience. This system enables “swarming” of users across contents (personal data, network channels, etc). It will result in a mode where the communities are defined implicitly and the zapper execution engine runs in a recommendation mode.  
      A final remark is that embodiments of the present invention are described above in terms of functional blocks. From the functional description of these blocks, given above, it will be apparent for a person skilled in the art of designing electronic devices how embodiments of these blocks can be manufactured with well-known electronic components. A detailed architecture of the contents of the functional blocks hence is not given.  
      While the principles of the invention have been described above in connection with specific apparatus, it is to be clearly understood that this description is merely made by way of example and not as a limitation on the scope of the invention, as defined in the appended claims.