Abstract:
A method of displaying an outcome of a game to a player comprising obtaining a stop position for each of a plurality of reels, each reel having a plurality of symbols at least one reel having a special symbol, each stop position specifying which symbol or symbols of each reel will correspond to a win line, displaying spinning of each reel to the reel&#39;s stop position, determining whether a special symbol condition is met, and making the display of the spinning of at least one subsequent reel different to display of at least the first reel if the special symbol condition is met.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to an Australian patent application filed on Oct. 20, 2006, as serial number AU2006230745, entitled “Gaming System and Method.” The foregoing application is herein incorporated by reference in its entirety. 
       FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    [Not Applicable] 
       MICROFICHE/COPYRIGHT REFERENCE 
       [0003]    [Not Applicable] 
       BACKGROUND OF THE INVENTION 
       [0004]    The present invention relates to a gaming system, a gaming method and a game controller. 
         [0005]    Australian patent 603193 discloses a poker machine having a means to cause each reel to turn to a stop in a position where a single line of symbols (one for each reel) is exhibited behind a viewing window. The poker machine has means for determining the length of time for which each reel is spun. If the same symbol is exhibited by a plurality of first stopped reels, normal operation of the machine is suspended and the time for which the next reel is spun is extended. Accordingly, in Australian patent 603193, spinning of a reel is extended in very limited circumstances. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    Certain embodiments of the present invention provide a method of displaying an outcome of a game to a player comprising: 
         [0007]    obtaining a stop position for each of a plurality of reels, each reel having a plurality of symbols at least one reel having a special symbol, each stop position specifying which symbol or symbols of each reel will correspond to a win line; 
         [0008]    displaying spinning of each reel to the reel&#39;s stop position; and 
         [0009]    determining whether a special symbol condition is met; and 
         [0010]    making the display of the spinning of at least one subsequent reel different to display of at least the first reel if the special symbol condition is met. 
         [0011]    In an embodiment, determining whether a special symbol condition is met comprises determining whether a special symbol will appear on a win line played by the player for a first reel. 
         [0012]    In an embodiment, determining whether a special symbol condition is met comprises determining whether a special symbol in combination with one or more symbols correspond to an initial portion of a predetermined game outcome and will appear on a win line played by the player after a predetermined number of reels have spun to a stop. 
         [0013]    In an embodiment, making the display different comprises altering at least one of the speed of spinning, the duration of spinning and the direction of spinning. 
         [0014]    Certain embodiments of the present invention provide a gaming system comprising: 
         [0015]    a stop determiner configured to determine a stop position of each of a plurality of reels, each reel having a plurality of symbols, each stop position specifying which symbol or symbols of the reel will correspond to a win line; 
         [0016]    a display for displaying spinning of each reel to the reel&#39;s stop position with at least a first reel being spun normally to the first reel&#39;s stop position; and 
         [0017]    a suspense mode controller configured to determine whether a special symbol condition is met and make the display of the spinning of at least one subsequent reel different to display of at least the first reel if the special symbol condition is met. 
         [0018]    In an embodiment, determining whether a special symbol condition is met comprises determining whether a special symbol will appear on a win line played by the player for a first reel. 
         [0019]    In an embodiment, determining whether a special symbol condition is met comprises determining whether a special symbol in combination with one or more symbols correspond to an initial portion of a predetermined game outcome and will appear on a win line played by the player after a predetermined number of reels have spun to a stop. 
         [0020]    In an embodiment, making the display different by altering at least one of the speed of spinning, the duration of spinning and the direction of spinning. 
         [0021]    Certain embodiments of the present invention provide a game controller for a gaming system, the game controller configured to: 
         [0022]    determine whether a special symbol condition is met based on a stop position for each of a plurality of reels, each reel having a plurality of symbols at least one reel having a special symbol, each stop position specifying which symbol or symbols of each reel will correspond to a win line; and 
         [0023]    make the display of the spinning of at least one subsequent reel different to display of at least the first reel if the special symbol condition is met. 
         [0024]    In an embodiment, determining whether a special symbol condition is met comprises determining whether a special symbol will appear on a win line played by the player for a first reel. 
         [0025]    In an embodiment, determining whether a special symbol condition is met comprises determining whether a special symbol in combination with one or more symbols correspond to an initial portion of a predetermined game outcome and will appear on a win line played by the player after a predetermined number of reels have spun to a stop. 
         [0026]    In an embodiment, making the display different by altering at least one of the speed of spinning, the duration of spinning and the direction of spinning. 
     
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0027]      FIG. 1  is a perspective view of a stand alone gaming machine according to an embodiment; 
           [0028]      FIG. 2  is a block diagram of the functional components of a gaming machine according to an embodiment; 
           [0029]      FIG. 3  is a schematic diagram of the functional components of a memory according to an embodiment; 
           [0030]      FIG. 4  is a schematic diagram of a network gaming system according to an embodiment; 
           [0031]      FIG. 5  is an exemplary display during a game in accordance with an example of an embodiment; 
           [0032]      FIG. 6  is a block diagram of the gaming system according to an embodiment; and 
           [0033]      FIG. 7  is a flowchart showing the method of an embodiment. 
       
    
    
       [0034]    The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, certain embodiments are shown in the drawings. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    Referring to the drawings, there is shown a gaming system arranged to implement a game having a suspense mode where display of at least one reel is made different to at least one other reel in response to occurrence of a special symbol condition in respect of one or more win lines played by the player. This can include a special symbol appearing on a first reel. 
         [0036]    The gaming system can take a number of different forms. 
         [0037]    In a first form, a stand alone gaming machine is provided wherein all or most components required for implementing the game are present in a player operable gaming machine. 
         [0038]    In a second form, a distributed architecture is provided wherein some of the components required for implementing the game are present in a player operable gaming machine and some of the components required for implementing the game are located remotely relative to the gaming machine. For example, a “thick client” architecture may be used wherein part of the game is executed on a player operable gaming machine and part of the game is executed remotely, such as by a gaming server; or a “thin client” architecture may be used wherein most of the game is executed remotely such as by a gaming server and a player operable gaming machine is used only to display audible and/or visible gaming information to the player and receive gaming inputs from the player. 
         [0039]    However, it will be understood that other arrangements are envisaged. For example, an architecture may be provided wherein a gaming machine is networked to a gaming server and the respective functions of the gaming machine and the gaming server are selectively modifiable. For example, the gaming system may operate in stand alone gaming machine mode, “thick client” mode or “thin client” mode depending on the game being played, operating conditions, and so on. Other variations will be apparent to persons skilled in the art. 
         [0040]    A gaming system in the form of a stand alone gaming machine  10  according to an embodiment is illustrated in  FIG. 1 . The gaming machine  10  includes a console  12  having a display  14  on which is displayed representations of a game  16  that can be played by a player. A mid-trim  20  of the gaming machine  10  houses a bank of buttons  22  for enabling a player to interact with the gaming machine, in particular during gameplay. The mid-trim  20  also houses a credit input mechanism  24  which in this example includes a coin input chute  24 A and a bill collector  24 B. Other credit input mechanisms may also be employed, for example, a card reader for reading a smart card, debit card or credit card. A reading device may also be provided for the purpose of reading a player tracking device, for example as part of a loyalty program. The player tracking device may be in the form of a card, flash drive or any other portable storage medium capable of being read by the reading device. 
         [0041]    A top box  26  may carry artwork  28 , including for example pay tables and details of bonus awards and other information or images relating to the game. Further artwork and/or information may be provided on a front panel  29  of the console  12 . A coin tray  30  is mounted beneath the front panel  29  for dispensing cash payouts from the gaming machine  10 . 
         [0042]    The display  14  shown in  FIG. 1  is in the form of a video display unit, particularly a cathode ray tube screen device. Alternatively, the display  14  may be a liquid crystal display, plasma screen, any other suitable video display unit, or the visible portion of an electromechanical device. The top box  26  may also include a display, for example a video display unit, which may be of the same type as the display  14 , or of a different type. 
         [0043]      FIG. 2  shows a block diagram of operative components of a typical gaming machine which may be the same as or different to the gaming machine of  FIG. 1  according to an embodiment. 
         [0044]    The gaming machine  100  includes a game controller  101  having a processor  102 . Instructions and data to control operation of the processor  102  are stored in a memory  103 , which is in data communication with the processor  102 . Typically, the gaming machine  100  will include both volatile and non-volatile memory and more than one of each type of memory, with such memories being collectively represented by the memory  103 . 
         [0045]    The gaming machine has hardware meters  104  for purposes including ensuring regulatory compliance and monitoring player credit, an input/output (I/O) interface  105  for communicating with peripheral devices of the gaming machine  100 . The input/output interface  105  and/or the peripheral devices may be intelligent devices with their own memory for storing associated instructions and data for use with the input/output interface or the peripheral devices. A random number generator module  113  generates random numbers for use by the processor  102 . 
         [0046]    In the example shown in  FIG. 2 , a player interface  120  includes peripheral devices that communicate with the game controller  101  comprise one or more displays  106 , a touch screen  107 , a card and/or ticket reader  108 , a printer  109 , a bill acceptor and/or coin input mechanism  110  and a coin output mechanism  111 . Additional hardware may be included as part of the gaming machine  100 , or hardware may be omitted as required for the specific implementation. 
         [0047]    In addition, the gaming machine  100  may include a communications interface, for example a network card  112 . The network card may, for example, send status information, accounting information or other information to a central controller, server or database and receive data or commands from the central controller, server or database. 
         [0048]      FIG. 3  shows a block diagram of the main components of an exemplary memory  103  according to an embodiment. The memory  103  includes RAM  103 A, EPROM  103 B and a mass storage device  103 C. The RAM  103 A typically temporarily holds program files for execution by the processor  102  and related data. The EPROM  103 B may be a boot ROM device and/or may contain some system or game related code. The mass storage device  103 C is typically used to store game programs, the integrity of which may be verified and/or authenticated by the processor  102  using protected code from the EPROM  103 B or elsewhere. 
         [0049]    It is also possible for the operative components of the gaming machine  100  to be distributed, for example input/output devices  106 , 107 , 108 , 109 , 110 , 111  to be provided remotely from the game controller  101 . 
         [0050]      FIG. 4  shows a gaming system  200  in accordance with an embodiment. The gaming system  200  includes a network  201 , which for example may be an Ethernet network. Gaming machines  202 , shown arranged in three banks  203  of two gaming machines  202  in  FIG. 5 , are connected to the network  201 . The gaming machines  202  provide a player operable interface and may be the same as the gaming machines  10 , 100  shown in  FIGS. 1 and 2 , or may have simplified functionality depending on the requirements for implementing game play. While banks  203  of two gaming machines are illustrated in  FIG. 4 , banks of one, three or more gaming machines are also envisaged. 
         [0051]    One or more displays  204  may also be connected to the network  201 . The displays  204  may, for example, be associated with one or more banks  203  of gaming machines. The displays  204  may be used to display representations associated with game play on the gaming machines  202 , and/or used to display other representations, for example promotional or informational material. 
         [0052]    In a thick client embodiment, game server  205  implements part of the game played by a player using a gaming machine  202  and the gaming machine  202  implements part of the game. With this embodiment, as both the game server and the gaming device implement part of the game, they collectively provide a game controller. A database management server  206  may manage storage of game programs and associated data for downloading or access by the gaming devices  202  in a database  206 A. Typically, if the gaming system enables players to participate in a Jackpot game, a Jackpot server  207  will be provided to monitor and carry out the Jackpot game. 
         [0053]    In a thin client embodiment, game server  205  implements most or all of the game played by a player using a gaming machine  202  and the gaming machine  202  essentially provides only the player interface. With this embodiment, the game server  205  provides the game controller. The gaming machine will receive player instructions, pass these to the game server which will process them and return game play outcomes to the gaming machine for display. In a thin client embodiment, the gaming machines could be computer terminals, e.g. PCs running software that provides a player interface operable using standard computer input and output components. 
         [0054]    Servers are also typically provided to assist in the administration of the gaming network  200 , including for example a gaming floor management server  208 , and a licensing server  209  to monitor the use of licenses relating to particular games. An administrator terminal  210  is provided to allow an administrator to run the network  201  and the devices connected to the network. 
         [0055]    The gaming network  200  may communicate with other gaming systems, other local networks, for example a corporate network, and/or a wide area network such as the Internet, for example through a firewall  211 . 
         [0056]    In certain embodiments, functionality at the server side of the network may be distributed over a plurality of different computers. For example, elements may be run as a single “engine” on one server or a separate server may be provided. For example, the game server  205  could run a random generator engine. Alternatively, a separate random number generator server could be provided. Further, in certain embodiments, a plurality of games servers could be provided to run different games or a single game server may run a plurality of different games as required by the terminals. 
         [0057]    Gaming systems for implementing games that involve a display of spinning reels as part of the display of the outcome of a game have either a video display or a mechanical display, these later machines most usually being “stepper” machines which have a separate motor for each reel. 
         [0058]    The game controllers of such gaming machines have a stop determining function that determines the stop position for each reel. For example, if there are five reels, each having twenty symbols, the stop determining function might determine that the stop positions are positions:  3 ,  13 ,  7 ,  9  and  17 . The spinning of the reels is then controlled so that each symbol comes to a stop in the same row, typically a predetermined row in a “window” visible to the player on the display that which corresponds to a player playing a single win line. When a reel stops, the symbols will be in one of a plurality of possible symbol positions for that reel relative to the stop position. 
         [0059]    Embodiments of the present invention relate to gaming systems that allow a player to select how many win lines of a plurality of win lines they will play in each game—i.e. a minimum of one win line up to the maximum number of win lines allowed by the game. Each win line is formed by a set of symbol positions consisting of one symbol position from each reel. That is, a predetermined symbol position of each reel is assigned to a win line. The symbol positions that constitute each of the win lines are usually advertised to the player by markings on the display or diagrams showing the symbol positions that correspond to each win line. Some of the win lines will be horizontal or diagonal lines but others may be non-linear combinations of symbols. Typically, the win lines will be constituted by symbol positions in the visible window. 
         [0060]      FIG. 6  shows the main functional components of a gaming system  600  of an embodiment. The game controller  605  includes a suspense mode controller  650  that controls whether the gaming system will enter a “suspense mode” where display of the spinning of at least one reel is controlled to be different to the spinning of another reel to thereby enhance game play. The suspense mode controller  650  determines which win lines the player has selected to play and then determines whether a suspense condition is met in relation to the player selected win lines. Depending on the nature of the suspense condition, it may be met in relation to a single win line or by a combination of win lines as described below. Certain embodiments relate to cases where the suspense condition is either a special symbol condition or, where there are plural suspense conditions, at least one of which is a special symbol condition. A “special symbol” is a symbol that has a particular impact on the game, for example, a wild symbol that can be substituted for any other symbol or a symbol that has a doubling effect on all prizes. One example of a special symbol condition may be that the special symbol appears on a win line after one of the first two reels spins to a stop. 
         [0061]    In order to play the game, the player enters credits using a credit mechanism in a conventional manner. The player then operates the player interface to specify the amount they want to bet per win line and the number of win lines they wish to play by operating a win line selector  660 . That is, the player may play one or a plurality of win lines up to the maximum number of win lines available for the game. For example if there are a maximum of three win lines, the player may play one, two or three win lines. A stop determiner  620 , obtains random numbers from the random number generator  610  and uses them to determine the stop position of each of the reels. As described above, the stop positions will specify which symbols of each reel will correspond to win lines. 
         [0062]    The stop positions are supplied by the stop determiner  620  to a reel controller  630  which controls the display of the spinning of individual reels to stop positions on display  640 . In normal operation of a video display this will result in a display where the reel is animated so that initially the reel is imperceptible to give the impression of spinning and then the symbols become perceptible so that a certain number of symbols (for example 6 symbols) can be viewed by the player before the reel reaches the stop position. In a mechanical display, the reel needs to be moved from its current stop position (from the previous game) to the new stop position. The duration and speed of spinning during a normal display of spinning will either be the same for each reel or within a normal range. 
         [0063]    As described in further detail below the reel controller  630  may also receive an adjustment instruction from suspense mode controller  650  which is used by the reel controller  630  to control the display of spinning of the reels to make display of at least one reel different. The stop positions are also provided to a game outcome processor  670 . The game outcome processor  670  processes the stop positions in accordance with the game rules  675  and the selected win lines to determine whether the player has won. The game outcome processor  670  alters meters  680  based on the game outcome and causes the prize outcome to be displayed on the display  640  once the reel controller  630  has caused the display  640  to display all reels spinning to a stop position. 
         [0064]    The suspense mode controller  650  determines whether one or more adjustment instructions are to be supplied to the reel controller  630  during a game. The adjustment instruction causes the reel controller  630  to alter the display of spinning of at least one reel. 
         [0065]    The suspense condition determiner  654  processes the win lines that are selected by win line selector  660  in conjunction with the reel stop positions produced by the stop determiner  620 , to thereby determine the symbols that will appear on win lines that a player has selected. 
         [0066]    This allows the suspense condition determiner  654  to determine whether a special symbol condition or another suspense condition will be met such as a predetermined game outcome appearing possible after a certain number of reels reach their stop positions. In an embodiment, the only suspense condition is a special symbol condition. By way of example, a special symbol condition may be that a special symbol appears on a specific reel or that a special symbol in combination with the other symbols corresponds to an initial portion of a winning symbol combination. Special symbol conditions  653 a are typically a subset of suspense conditions  653 . For example, the suspense condition determiner  654  may run a specific sub routines to monitor for each suspense condition being monitored. For example, a sub-routine to count a number of symbols of a certain type. If a suspense condition is satisfied, adjuster  656  determines an adjustment and supplies it to the reel controller  630 . If in a specific embodiment only one type of adjustment is applied, the adjuster can send an adjustment instruction to the reel controller  630  which is configured to make the relevant adjustment. Depending on the embodiment the adjuster  656  may calculate the adjustment based on a predetermined formula or obtain the relevant adjustment from adjustment data  657  and send it as an adjustment instruction specifying the adjustment to reel controller  630  for implementation. 
         [0067]    Referring to the flow chart in  FIG. 7  of an embodiment, at step  710  a new game is started. At step  720  a player operates the win line selector to select a number of lines to play. At step  730  the stop determiner determines the stops and supplies data specifying these to the reel controller and the possible outcome processor. At step  740  the suspense conditioner determines whether a special symbol condition or other suspense condition that is monitored exists and hence whether the adjuster should generate adjustment data based on the possible outcomes. If no suspense conditions are met the process stops  750  for this game. If one or more suspense conditions are met, at step  760  the adjuster determines an adjustment and supplies it to the reel controller as adjustment data. At step  770  the reel controller controls displays of spinning of each reel to the stop position based on the stops and adjustments. At step  780  the game ends. 
         [0068]    Suspense Conditions 
         [0069]    Other suspense conditions may be based on a predetermined game outcome being possible after one or more reels are spun to a stop position. The game outcome may be an entry in a pay table for the game or may be a value derived from the pay table such as a prize threshold. The number of reels that are required to have reached the stop position may form part of the suspense condition. If a prize is awarded for five symbols of the same type, it may be appropriate to trigger a suspense condition after two or three symbols of the same type have been spun to a stop on the same win line. 
         [0070]    A suspense condition may be based on the predetermined game outcome being that a prize is above a particular threshold value. For example, the suspense condition determiner  654  may determine a number of possible game outcomes in the pay table appear possible after three of the reels have spun to a stop and based on the associated prizes determines whether any of the prizes are above a preset threshold. 
         [0071]    A suspense condition may be based on a combination of two or more factors, for example the size of the prize corresponding to the outcome that appears possible and how likely it appears after a reel has spun to a stop that the player will win the prize; that is, based on the probability of the outcome occurring. 
         [0072]    By way of specific example, in one game a prize may be awarded for five aces and may be the maximum prize for that game. A lesser prize may be awarded for four aces. A suspense condition may be set in relation to the five ace prize, so that if the first three reels each have aces on a win line, a suspense mode may be triggered. That is, the five ace prize appears to be possible after three reels and is judged to be sufficiently likely once the first three reels have aces. If the first three reels are two aces and a king, suspense mode is not entered into and suspense mode will only be entered into if three of the first four reels are aces because it is not until the fourth reel that it is deemed that it will appear sufficiently likely that they will win the four ace prize and hence it is deemed appropriate to enter the suspense mode in view of the size of the prize. In this example, for a higher prize a relatively lower likelihood is sufficient to trigger a suspense mode. 
         [0073]    The above suspense conditions relate to a symbol combination on a single win line, however the suspense condition may based on multiple win lines. For example, in one embodiment a suspense mode may only be entered into if a game outcome from the pay table appears possible in relation to two or more win lines played by a player. That is, a subset of all winning outcomes specified in the pay table may be sufficient to initiate a suspense mode if two or more such winning outcomes appear possible for different win lines. 
         [0074]    Alternatively, it may be required that the total of the win outcomes that appear possible across all win lines played by the player exceed a prize threshold such that possible outcomes from separate wins can contribute to that total. That is, apparent game outcomes with prizes below the threshold on an individual win line will not trigger a suspense mode but if the total of prizes that appear possible after a certain number of reels exceeds the threshold the suspense mode may be entered into. Different thresholds may be set for different numbers of reels having spun to a stop and/or different numbers of win lines. 
         [0075]    Adjustments 
         [0076]    The display may be adjusted by altering the duration of the spinning of one or more reels. For example, if two aces appear on the first reel and second reels, the duration of spinning of the third reel may be extended. 
         [0077]    Alternatively, the speed of spinning or a reel may be adjusted. For example, if aces appear on the first four reels, the duration of the spinning of the fifth reel may be the same but the speed of the spinning of the fifth reel may be slowed so that the player can more readily perceive the symbols on the reel as they move into position or sped up as an indicator of excitement. 
         [0078]    Another possible adjustment of the display is to reverse the direction of spinning of the reel. 
         [0079]    It is possible to combine variations of spinning. For example, in an example where a winning outcome appears possible on multiple reels, if a winning outcome appears possible on one reel, the duration may be altered but if it appears possible on two win lines, both duration and speed may be altered. 
         [0080]    In certain embodiments, multiple duration and multiple speed variations may be possible. The adjuster  656  may determine a size of an adjustment dependent on:
       a) the size of the prize;   b) the number of reels in relation to which a suspense condition is met;   c) a number of suspense conditions that are met; or   d) the likelihood of a prize outcome.       
 
         [0085]    For example, in a case where five aces appear on a reel, the duration of the spin may be extended for a first time after two aces appear, a second time after three aces appear and a third time once four aces appear and it appears highly likely the player will win the prize corresponding to five aces. 
         [0086]    A suspense mode will be ended if a suspense condition is no longer met and there are more reels to be spun. 
       EXAMPLE  
       [0087]    Referring to  FIG. 5  there is shown an exemplary display  500  that may occur during a game according to an embodiment. In the gaming machine of  FIG. 5  five lines of symbols  520 A to  520 E are displayed on the display once all reels have spun to a stop. There are five reels  510 A to  510 E. While five lines are displayed, only three lines  530 A,  530 B and  530 C are win lines. If the player selects to play one win line, they play win line one  530 A. Win line two  530 B is also played if they select two win lines and win line three is added  530 C if they select three win lines. 
         [0088]    Consider an example where a player selects to play two win lines. In this example a suspense mode is initiated if a Joker symbol appears on one of the first two reels of a win line and continues until a win line has two different symbols that are not jokers. As the player is only playing two win lines, suspense mode can only be activated in relation to these win lines. Assume that reels one to five  510 A to  510 E are spun to a stop in numerical order. In certain embodiments, the order of the reels displayed may be varied depending on the embodiment. Once reel one has spun to a stop, suspense mode is activated because the player has a Joker on win line two. In this game a Joker acts as a wild symbol which may be substituted for any of the other symbols. Thus irrespective of the symbol that appears on win line two on reel two, the player will have an increased apparent chance of winning. After reel two spins to a stop there are two jokers on win line two and suspense mode is maintained. After reel three, there is a King and two Jokers on win line two and the suspense mode is maintained. When reel four spins to a stop, a suspense condition is no longer met in relation to win line two because there are two different symbols apart from the Joker and hence a player can no longer obtain five of the same symbols on win line two. Accordingly the machine reverts to normal display mode. 
         [0089]    Various modifications will be apparent to persons skilled in the art, and should be understood as falling within the scope of the appended claims. 
         [0090]    For the purposes of this specification it will be clearly understood that the word “comprising” means “including but not limited to”, and that the word “comprises” has a corresponding meaning. 
         [0091]    It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. 
         [0092]    While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.