Abstract:
A method for distributing digital content is disclosed. The method includes receiving, at an operator of a wireless communications network, a request for digital content from a first mobile device. The method further includes determining, at the operator, that a second mobile device has the digital content. The method further includes receiving the digital content from the second mobile device at the operator of the wireless communications network and sending a message including a pointer related to the digital content to the first mobile device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority from and is a continuation of pending U.S. patent application Ser. No. 11/137,916, filed May 26, 2005, the content of which is incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present invention relates to a method and system for digital content distribution/transactions, and more particularly to generating revenue based on distributing digital content stored in a subscriber&#39;s mobile device and when the subscriber&#39;s mobile device is connected to a network. 
       BACKGROUND 
       [0003]    Rapid improvements in digital technology have changed the way information is shared and distributed. From newspapers to photographs, users in every aspect of today&#39;s modern life use digital content. The popularity of the Internet and the use of mobile devices (for example, cellular phones, personal digital assistants and other devices), have further increased the demand for digital content. Digital content producers/providers face various challenges to control and distribute digital content, while keeping abreast with evolving business models to generate profit. Digital Rights Management (“DRM”) involves management of digital rights including physical manifestation of digital content (for example, a textbook or an article). DRM techniques are used to control access to digital content by enforcing controlled environments and/or encoding digital content. 
         [0004]    Various standards are being used and developed to control, monitor and capitalize on digital content distribution in the commercial world, especially involving mobile devices. The following describes some of these standards. 
         [0005]    The Open Digital Rights Language (ODRL) is a standard DRM architecture (incorporated herein by reference in its entirety) for protecting digital content in an open or trusted computing environment. ODRL defines a standard vocabulary for expressing the terms and conditions over an asset (digital content). Rights can be specified for a specific asset manifestation or format or could be applied to a range of manifestations—of the asset. ODRL does not enforce or mandate any policy for DRM, but provides mechanisms to express such a policy. ODRL does not presume that mechanisms exist to achieve a secure architecture, but complements existing rights management standards by providing digital equivalents and supports an expandable range of new services that can be afforded by the digital nature of the assets in the Web environment. In the physical environment, ODRL can enable machine-based processing for DRM. The information about ODRL, as well as, ODRL electronic resources such as the ODRL Specification (version 1.1), the ODRL Data Dictionary (version 1.1), and the ODRL Expression Language (version 1.1), are incorporated herein by reference in their entirety. 
         [0006]    The eXtensible Markup Language (XML) (incorporated herein by reference in its entirety) is a standard for exchanging data and metadata electronically, where metadata describes the data. For example, the term “writer” is metadata that describes the data “CS Lewis”. XML is an outgrowth of the Standard Generalized Markup Language (SGML) that allows the author of an XML document to separate the logical content of the document from the presentation of the content. An author of an XML document adds metadata to a document as hypertext transfer protocol (HTTP) tags in the document. A document type definition (DTD) file is the mechanism that adds shared content to the XML document. 
         [0007]    The extensible rights Markup Language (XrML) (incorporated herein by reference in its entirety) is an XML conforming language definition that specifies rights, fees, and conditions for using digital content. XrML also describes message integrity and entity authentication rules. XrML supports commerce in digital content such as publishing and selling electronic books, digital movies, digital music, interactive games, and computer software. 
         [0008]    The Open Mobile Alliance (“OMA”), a standard organization was created by consolidating the efforts of the supporters of the Open Mobile Architecture initiative and the WAP Forum with the SyncML initiative, Location Interoperability Forum (LIF), MMS Interoperability Group (MMS-IOP), Wireless Village, Mobile Gaming Interoperability Forum (MGIF), and Mobile Wireless Internet Forum (MFIW). The OMA provides an overall standard architecture (incorporated herein by reference in its entirety) that compliments existing communication standards, such as 3GPP or CDMA and also provides guidelines for controlling a mobile device, delivering and protecting content, and assists in commercial transactions using a mobile device. The term Mobile Commerce (“M-Commerce”) as used throughout this specification means the exchange or buying and selling of services and goods including subscription services, both physical and digital, from a mobile device. 
         [0009]    Conventional digital content transactions involve a mobile device user (or subscriber, used interchangeably throughout this specification) who places an order for content. The subscriber obtains the rights from a rights issuing authority and content from a digital content provider via a mobile network operator (“MNO”). The rights associated with the content determine how the user can use or share the content. For example, the rights granted by the rights issuing authority may allow the subscriber to share the content with others (or “peers”) using a peer-peer network. 
         [0010]    In a peer-to-peer network, the subscribers are connected to each other and mobile devices can exchange data/information. A peer-to-peer network allows content to be stored/shared among subscribers using a mobile network besides a phone-to-phone connection. 
         [0011]    As digital content related transactions become more popular, digital content providers will need new innovative business techniques to increase revenue and profits. Conventional business models fail to capitalize or generate revenue based on content stored in a subscriber&#39;s mobile device. Once, content is downloaded by the subscriber, the content provider or the subscriber, does not generate any more revenue based on the downloaded content. Instead of utilizing the downloaded content for generating extra revenue, conventional techniques have tried to restrict content sharing in a peer-to-peer environment. 
         [0012]    Therefore, there is a need for a method and system that will allow content stored by a subscriber to be re-circulated among other subscribers, hence, providing a new source of revenue for the parties that are involved in the transaction, namely, the content provider, the MNO, the rights issuing entity and the subscriber whose stored content is licensed/distributed to another subscriber. 
       SUMMARY 
       [0013]    In a particular embodiment, a method for distributing digital content is disclosed. The method includes receiving, at an operator of a wireless communications network, a request for digital content from a first mobile device. The method further includes determining, at the operator, that a second mobile device has the digital content. The method further includes receiving the digital content from the second mobile device at the operator of the wireless communications network, and sending a message including a pointer related to the digital content to the first mobile device. 
         [0014]    In another particular embodiment, a method for distributing digital content is disclosed. The method includes receiving a request for digital content from a first mobile subscriber. The method further includes identifying a second mobile subscriber that has access to the digital content, and determining whether the second mobile subscriber is connected to a network when the request for digital content is received. The method further includes receiving the digital content at an operator from the second mobile subscriber on behalf of the first mobile subscriber. The method further includes communicating a link associated with the digital content to the first mobile subscriber. The method further includes delivering the digital content to the first mobile subscriber, and sending access rights to the first mobile subscriber so that the first mobile subscriber can use the delivered digital content. 
         [0015]    In another particular embodiment, a method for distributing digital content is disclosed. The method includes receiving a request for digital content at a mobile network operator from a first mobile device. The method further includes identifying a second mobile device that has access to the digital content, and receiving the digital content at the mobile network operator from the second mobile device. The method further includes updating a link to a rights package associated with the digital content, and communicating the link to the rights package to the first mobile device. The method further includes delivering the digital content to the first mobile device from the mobile network operator. The method further includes sending a request to a content source for the rights package associated with the requested digital content, and sending the rights package to the first mobile device to enable the first mobile device to use the delivered digital content. 
         [0016]    Other aspects, advantages, and features of the present disclosure will become apparent after review of the entire application, including the following sections: Brief Description of the Drawings, Detailed Description, and the Claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The foregoing features and other features of the present invention will now be described with reference to the drawings of a preferred embodiment. In the drawings, the same components have the same reference numerals. The illustrated embodiment is intended to illustrate, but not to limit the invention. The drawings include the following Figures: 
           [0018]      FIG. 1A  shows a block diagram of a system for conducting transactions involving digital content, according to one aspect of the present invention; 
           [0019]      FIG. 1B  shows a block diagram of a computing system used in the system of  FIG. 1A , according to one aspect of the present invention; 
           [0020]      FIG. 1C  shows the internal architecture of the computing system of  FIG. 1B ; 
           [0021]      FIG. 1D  shows a block diagram of a system for conducting transactions for digital content, according to one aspect of the present invention; 
           [0022]      FIG. 1E  shows another example of a system for conducting transactions involving digital content, according to one aspect of the present invention; 
           [0023]      FIG. 2A  shows a block diagram of a mobile device used in the system of  FIG. 1A ; 
           [0024]      FIG. 2B  shows a block diagram of a memory used in the mobile device of  FIG. 2A ; 
           [0025]      FIG. 3  shows a process flow diagram of conducting a transaction involving digital content, according to one aspect of the present invention; 
           [0026]      FIG. 4  is a block diagram showing a right package (or oblect) manipulation, according to one aspect of the present invention; and 
           [0027]      FIG. 5  shows an example of how cipher keys are distributed, according to one aspect of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    To facilitate an understanding of the preferred embodiment, the general architecture and operation of a system that allows re-distribution of digital content stored in a subscriber&#39;s mobile device will be described. The specific architecture and operation of the preferred embodiment will then be described with reference to the general architecture. 
         [0029]    Overall System: 
         [0030]      FIG. 1A  shows a block diagram of the overall system  100  that is used according to one aspect of the present invention. In  FIG. 1A , a mobile device A  101  (also referred to as “device  101 ” or “mobile device  101 ” or as the “source mobile device”) (used by a subscriber that may be referred to as “subscriber A” or “User A”) and a mobile device B  102  (also referred to as “device  102 ” or “mobile device  102 ”) (used by a subscriber that may be referred to as “subscriber B” or “User B”) are operationally coupled to MNO  103 . Mobile devices may connect to a content provider/server ( 105 ) via MNO  103  or any other type of network, for example, the Internet, Wi-Fi or the like. 
         [0031]    MNO  103  receives requests from a subscriber and delivers digital content, as described below. MNO  103  is operationally coupled to system  104  that includes a digital content provider  105  (may also be referred to as module  105 ) and rights issuing authority  106  (may also be referred to as “module  106 ”, “Rights Issuer  106 ”, “RI” or “Rights Issuing Authority”). It is noteworthy that modules  105  and  106  may be functionally/physically separate or integrated in a single computing system. 
         [0032]    User B sends a request to MNO  103  for certain digital content. MNO  103  searches for content based on the request and determines if another user (for example, User A) has the requested content. If User A is connected to the network at the time of User B&#39;s request and has the requested content, then MNO  103  obtains the essential rights for re-distributing the requested content to User B. MNO  103  may get the content from User A or send it directly to User B from content provider  105 . 
         [0033]    In one aspect of the present invention, User A is given a certain percentage of the license price/transaction cost. The content provider (i.e. the entity hosting module  105 ) and MNO  103  also get a certain percentage of the license price. 
         [0034]    The adaptive aspects of the present invention are not limited to the topology of  FIG. 1A . Various modifications may be used, for example, as shown in  FIGS. 1D and 1E , described below. 
         [0035]      FIG. 1D  shows system  100 A with a content operator  103 A that co-ordinates digital data exchange between plural subscribers. Content operator  103 A may charge each subscriber a fee to participate in a “content exchange program”, which allows each subscriber to license/re-distribute content that is stored locally on a subscriber&#39;s mobile device or to which a subscriber has access. 
         [0036]    Subscribers (for example, User A and User B) directly interface with content operator  103 A via a network  103 B. In this configuration, content operator  103 A may interface with module  106  to obtain the rights package for digital content and content may be delivered via MNO  103  or network  103 B. 
         [0037]    In another aspect of the present invention, subscribers may choose to go through MNO  103  that interfaces with content operator  103 A. Also, subscribers (User A and User B) may directly exchange digital content using network  103 B and content operator  103 A. 
         [0038]      FIG. 1E  shows another example of a topology ( 100 B), where mobile devices  101  and  102  may exchange digital content via a network  107 . An operator  108  facilitates the transactions between the subscribers, and MNO  103  may not be required. In system  100 B, network  107  may be any proprietary or public network that couples devices  101  and  102  to operator  108  that is coupled to system  104 . 
         [0039]    Computing System: 
         [0040]    Typically, modules  105 / 106  are a computing system where digital content is stored.  FIG. 1B  shows a block diagram of a computing system (may also be referred to as “computer”) that may be used by modules  105 / 106  (and MNO  103 ), according to one aspect of the present invention.  FIG. 1B  includes a computer  10  and a monitor  11 . Monitor  11  may be a CRT type, a LCD type, or any other type of color or monochrome display. Also provided with computer  10  are a keyboard  13  for entering text data and user commands, and a pointing device  14  for processing objects displayed on monitor  11 . 
         [0041]    Computer  10  includes a computer-readable memory medium  15  such as a rotating disk/tape for storing readable data/digital content. Besides other programs, media  15  can store application programs, digital content, security algorithms and any other interface used for implementing the adaptive aspects of the present invention. 
         [0042]    Computer  10  can also access another computer-readable media  16  (for example, a floppy disk, CD-ROM, flash memory or any other media) storing data files, application program files, and computer executable process steps embodying the present invention. A CD-ROM/CD-Read-Write interface (not shown) may also be provided with computer  10  to access application program files, and data files stored on a CD. 
         [0043]    A modem, an integrated services digital network (ISDN) connection, Wi-Fi or the like also provides computer  10  with a network connection  12 . In one aspect, the network connection  12  allows computer  10  to access the World Wide Web (WWW) via the Internet. Network connection  12  allows computer  10  to download data files, application program files and computer-executable process steps. 
         [0044]      FIG. 1C  is a block diagram showing the internal functional architecture of computer  10 . As shown in  FIG. 1C , computer  10  includes a CPU  20  for executing computer-executable process steps and also interfaces with a computer bus  21 . Also shown in  FIG. 1C  are a video interface  22 , a printer interface  24 , a storage device interface  23 , a Network interface  25 , an application interface  26 , a display device interface  27 , a keyboard interface  28 , and a pointing device interface  29 . 
         [0045]    Application interface  26  may be used to interface with security algorithms/hardware for securing digital content. Storage interface  23  may be used for interfacing computer  10  with mass storage area networks (not shown). The network interface  25  allows computer  10  to connect to a network via network connection  12 . 
         [0046]    As described above, media  15  stores operating system program files, application program files, web browsers, and other files. Some of these files are stored on media  15  using an installation program. For example, CPU  20  executes computer-executable process steps of an installation program so that CPU  20  can properly execute the application program. 
         [0047]    A random access main memory (“RAM”)  30  also interfaces to computer bus  21  to provide CPU  20  with access to memory storage. When executing stored computer-executable process steps from media  15  (or other storage media  16  or via network connection  12 ), CPU  20  stores and executes the process steps out of RAM  30 . 
         [0048]    Read only memory (“ROM”)  31  is provided to store invariant instruction sequences such as start-up instruction sequences or basic input/output operating system (BIOS) sequences. 
         [0049]    The foregoing description of computer  10  is intended to provide a general description of a computing system that may be used in system  100 . Various modifications may be used to implement the adaptive aspects of the present invention. Other configurations may be used and may have additional or fewer components than those described above with respect to FIG.  1 B/ 1 C. For example, a server (used by modules  105 / 106 ) may not use a keyboard or a display device and may be administered remotely by another computing system. 
         [0050]    Mobile Device: 
         [0051]      FIG. 2A  shows a block diagram of a mobile device (for example  101 ) that is used according to one aspect of the present invention. Mobile device  101  is a general purpose wireless device, which includes cellular phones and PDAs. Mobile device  101  includes a local bus  201 A that connects various other components, including keypad  202 , display module  203 , network interface  204 , and processor  201 . A data storage device  205  may also be provided and may include flash memory cards and/or other memory devices. 
         [0052]    There are currently many different flash memory cards that are commercially available, examples being the CompactFlash (CF), the MultiMediaCard (MMC), Secure Digital (SD), miniSD, Memory Stick, SmartMedia and TransFlash cards. Although each of these cards has a unique mechanical and/or electrical interface according to its standardized specifications, the flash memory included in each is very similar. These cards are all available from SanDisk Corporation, assignee of the present application. Network interface  204  allows connectivity between mobile device  101  and any network. 
         [0053]    Processor  201  performs the methods of the disclosed invention by executing sequences of operational instructions resident in memory  206 . 
         [0054]    As shown in  FIG. 2B , memory  206  includes an operating system  207 , interface software  208  and application software  209 . Operating system  207  includes embedded software and low-level system software that controls mobile device  101  and communication with other components, for example, keypad  202  and display  203 . 
         [0055]    Application software  209  includes a user interface (not shown) that allows a user to conduct digital content related transactions including requesting digital content from MNO  103 , according to one aspect of the present invention. Application software  209  and interface software  208  include security modules that allow a user to safely conduct digital content related transactions. 
         [0056]    Application software  209  allows a user to use the Internet to conduct transactions and computer-executable process steps, according to one aspect of the present invention. 
         [0057]    The following provides a brief description of the Internet. It is noteworthy that the Internet is just one way to deliver content, according to the adaptive aspects of the present invention, and is not intended to limit the present invention. Any other network, including proprietary networks used by MNOs, TCP/IP, PABX or the like may be used to conduct the commercial transactions, according to the adaptive aspects of the present invention. 
         [0058]    The Internet connects thousands of computers world wide through well-known protocols, for example, Transmission Control Protocol (TCP)/Internet Protocol (IP), into a vast network. Information on the Internet is stored world wide as computer files, mostly written in the Hypertext Mark Up Language (“HTML”). Other mark up languages, e.g., Extensible Markup Language as published by W3C Consortium, Version 1, Second Edition, October 2000, ©W3C may also be used. The collection of all such publicly available computer files is known as the World Wide Web (WWW). 
         [0059]    The WWW is a multimedia-enabled hypertext system used for navigating the Internet and is made up of hundreds of thousands of web pages with images, text and video files, which can be displayed on a computer monitor/mobile device  111 . Each web page can have connections to other pages, which may be located on any computing device connected to the Internet. 
         [0060]    A typical Internet user uses a client program called a “Web Browser” to connect to the Internet. A user can connect to the Internet via a proprietary network or via an Internet Service Provider. A Web Browser may run on any computing device connected to the Internet. Currently, various browsers are available of which two prominent browsers are Netscape Navigator® and Microsoft Internet Explorer®. 
         [0061]    The Web Browser receives and sends requests to a web server and acquires information from the WWW. A web server is a program that, upon receipt of a request, sends the requested data to the requesting user. A standard naming convention known as Uniform Resource Locator (“URL”) has been adopted to represent hypermedia links and links to network services. Most files or services can be represented with a URL. 
         [0062]    URLs enable Web Browsers to go directly to any file held on any WWW server. Information from the WWW is accessed using well-known protocols, including the Hypertext Transport Protocol (“HTTP”), the Wide Area Information Service (“WAIS”) and the File Transport Protocol (“FTP”), over TCP/IP protocol. The transfer format for standard WWW pages is Hypertext Transfer Protocol (HTTP). 
         [0063]    Process Flow: 
         [0064]      FIG. 3  shows a process flow diagram for conducting digital content delivery transactions, according to one aspect of the present invention. In step S 300 , a subscriber (for example, User B of mobile device  102 ) sends a request for digital content to MNO  103 . User B may use Application Software  209  to send the request. In another aspect of the present invention, requests may be sent to content operator  103 A ( FIG. 1D ) or operator  108  ( FIG. 1E ). 
         [0065]    In step S 302 , MNO  103  searches for content. MNO  103  determines if the requested content is available from another user (for example, User A using mobile device  101 ). If another user (for example, User A) has the requested content, then in step S 304 , MNO  103  acquires content from mobile device  101  (or module  105 ) and updates the content package, as described below with respect to  FIG. 4 , after determining that the content can be sourced/redistributed from the mobile device ( 101 ). 
         [0066]    It is noteworthy that MNO  103  may deliver content from module  105  instead of mobile device  101  due to bandwidth restrictions and for improving the content downloading rate. In this case MNO  103  traces the content or updates the URL to the rights package, as discussed below in detail with respect to  FIG. 4 . 
         [0067]    In step S 306 , a request for the rights package associated with the requested content is sent to module  106  and the process moves to step S 310 . 
         [0068]    In step S 310 , MNO  103  delivers the rights package that is received from module  106  to User B. This allows User B to use the digital content received in step S 304 . User A is compensated for the content that is licensed and sent to User B. MNO  103  and content provider  105  also get a percentage of the transaction. 
         [0069]    If another connected subscriber (for example, User A) does not have content in step S 302 , then in step S 308 , MNO  103  acquires the content from content provider  105  and delivers it to User B and the process moves to step S 306 . Also, in this aspect, in step S 310 , only the content provider  105 , RI  106  and MNO  103  are compensated for the transaction. 
         [0070]      FIG. 4  shows a block diagram of a rights package (“RP”)  400 , protected digital content package (“PDCP”)  401  and the modified PDCP  402  that is used, according to one aspect of the present invention. RP  400  is issued by module  106  and includes a set a permissions that are associated with specific content. RP  400  also includes a cipher key  400 A that is used for deciphering the digital content. RP  400  further includes a pointer that points to protected digital content  401 A. It is noteworthy that the present invention is not limited to any particular cipher key/algorithm/methodology. RP  400  also includes information regarding the entity that issues the rights (rights issuer information). 
         [0071]    PDCP  401  includes a URL for module  106 . It also includes content and information that describes (or related) the digital content. Optionally, PDCP  401  may also include information that shows an integrity check for the content has been completed. This allows content to be signed or unsigned, depending on whether the integrity check is included in PDCP  401 . 
         [0072]    In Modified PDCP  402 , the protected content (shown as  402 A) includes a pointer (shown as “X”) that points to the rights issuer and provides information about the source of the protected digital content (for example, mobile device  101 ). RI URL′ is concatenated with a pointer to the content source (for example, mobile device  101 ) and the original RP  400  is not changed. 
         [0073]    A new cipher key may be stored and used to access the stored content from User A. The new cipher key may be kept with mobile device  101 . The original cipher key (from module  106 ) and the new cipher key (from mobile device  101 ) may be used by User B to decipher/access content. 
         [0074]      FIG. 5  shows an example of how cipher keys may be used to access protected content by mobile device  102 . Module  106  sends original content cipher key  400 A to mobile device  101  (shown as  500 ). A local cipher key  400 B is generated by mobile device  101  and can be used to protect content  402 A. 
         [0075]    When content ( 402 A) is transferred from mobile device  101  to mobile device  102 (shown as  501 ), then the content can be protected by the original cipher key  400 A or by using local cipher key  400 B. If only the original cipher key  400 A is used then mobile device  102  obtains the original cipher key from module  106  to decipher the protected content. 
         [0076]    If the original cipher key  400 A is not used, then mobile device  192  uses the local handset cipher key  400 B is used to access content. 
         [0077]    The adaptive aspects of present invention are not limited to the foregoing topologies/process steps, various modifications/options may be used so that a subscriber that has content and is connected to a network at a given instance benefits from a transaction. The following provides a few examples of the various modifications: 
         [0078]    Protected digital content may be marked and redistributed; or marked, signed (with an integrity check) and distributed. 
         [0079]    A user mobile device (for example,  101 ) may become the rights issuing authority  106  after it updates a cipher key that is related to protected digital content. In this situation, module  106  is compensated when the request for the rights is made, and MNO  103  may compensate module  106 . 
         [0080]    A local cipher key ( 400 B) and the original cipher key  400 A are used to secure access to content. In this case, MNO  103  may obtain the rights from module  106  and an updated cipher key from mobile device  101 . MNO  103  then delivers an updated rights package. In another aspect, MNO  103  acquires the rights from module  106  and key from mobile device  101 , and then creates a rights package. This rights package is sent to mobile device  102 . 
         [0081]    In another aspect of the present invention, a database for module  106  is updated with a new reference (i.e. the rights package and the new source (mobile device  101 ). However, the new rights package may have an expiration date. Even when the new rights package expires, the original cipher key/rights package is maintained and stored by module  106 . In this aspect of the present invention, rights are renewed without interfacing with mobile device  101  (the original mobile device). Mobile device  101  may deliver empty rights (i.e. without a cipher key) and the original cipher key ( 400 A) is used to access the content. The newly delivered rights are then updated and stored again. 
         [0082]    In yet another aspect, different parts of the PDCP  401  are received from plural subscribers and the subscribers are compensated accordingly. 
         [0083]    In one aspect of the present invention, User A benefits from storing the content in mobile device A  101  and by being connected to the network, at the instance User B sends a request for content. 
         [0084]    Content provider  105  also benefits from this model, because more subscribers like User A will license and store digital content hoping that while they are connected, a request for the stored content will originate and they will benefit from the transaction described above. MNO  103  gets a percentage of the transaction as well. Furthermore, module  106  gets additional revenue based on additional requests for rights package to access/decipher digital content. 
         [0085]    Therefore, this is a “win-win” revenue sharing model where all the parties involved in digital content stored in a subscriber&#39;s mobile device benefit. 
         [0086]    While the present invention is described above with respect to what is currently considered its preferred embodiments, it is to be understood that the invention is not limited to that described above. To the contrary, the invention is intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims.