Patent Publication Number: US-6661434-B1

Title: Method and system for displaying status of critical indicators on diverse display devices

Description:
This application is related to the following copending U.S. Patent Applications, filed on even date herewith: Ser. No. 09/548,694 entitled “Method and System for Displaying Status of Critical Indicators on Diverse Display Devices and Indicating Changes in Status” by MacPhail, and Ser. No. 09/548,695 entitled “Method and System for Displaying Status of Critical Indicators on Diverse Display Devices and Indicating a History of Status Changes” by MacPhail. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to information display, and more particularly to a method and system for displaying the status of variables, or indicators, on diverse display devices. This method may be useful for multiple applications involving information display, including, for example, platform management in heterogeneous systems. 
     2. Description of the Related Art 
     The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section. 
     The continuing proliferation of powerful, convenient computational devices has been accompanied by an increase in the use of networks connecting these devices. Computational devices include computers and other, often portable, devices such as wireless telephones, personal digital assistants (PDA&#39;s), automobile-based computers and appliance-based computers. Such computational devices are also sometimes termed “pervasive devices”. “Computer”, as used herein, may refer to any of such computational devices. The networks connecting computational devices may be “wired” networks, formed using “land lines” such as copper wire or fiber optic cable, wireless networks employing earth and/or satellite-based wireless transmission links, or combinations of wired and wireless network portions. Networked computational devices are increasingly configured with the ability to interact and communicate with one another. For example, electronic mail may currently be sent to some wireless telephones and pagers, and PDA&#39;s may be used to access some Internet and World Wide Web (or “web”) sites. 
     Many network-based applications involve monitoring variables of interest, which may be called “critical indicators”. For example, a system administrator for a computer system or network may need to monitor variables such as transaction rates, application program status, and disk space availability. Such variables may be considered critical indicators in that they are important indicators of the health of the system or network. Alternatively, an investor may wish to monitor a variable such as a stock price, and may particularly want to be alerted if the price rises above or falls below a particular critical value. Entertainment-oriented applications may also involve monitoring of critical indicators. For example, a horse-racing enthusiast may wish to know whether a particular race has started or finished, and/or whether a particular horse has placed above or below a particular level. Monitoring of such critical indicators using a computational device is typically done through a graphical user interface (GUI) on the device&#39;s display screen. Many different display formats are possible. For example, a bar graph could be used to indicate values of various indicators, where the heights of the bars vary with time to follow the indicator values. Icons representing each indicator may also be displayed on a screen, where selection of an icon by a user results in a text display containing information regarding the status of the indicator. To indicate when a variable has crossed a threshold value, various methods may be used, such as changing the shape or color of an icon representing the variable, or not displaying an icon unless the corresponding variable has crossed a threshold value. 
     The above-described methods of monitoring critical indicators may result in difficulties, however, for users of diverse computational devices having varying display screen capabilities. The trend in size and capability of such display screens often depends upon whether the device is fixed or portable. For example, displays associated with desktop computers are generally getting larger, to provide ease of viewing and/or accommodate increasingly complex applications and operating systems. Such displays typically have a wide range of colors available, as well. On the other hand, displays associated with portable devices such as wireless telephones and PDA&#39;s are small and often getting smaller, to enhance, e.g., portability and battery life. These small displays also tend to be monochrome displays rather than color, because of cost, resolution and power considerations. Although not necessarily portable, displays included in automobiles or appliances may also be small monochrome displays, to keep costs down and avoid taking space needed for other functions of the system. This variation in display size and capability for different computational devices means that a GUI which allows effective monitoring of critical indicators when a system administrator&#39;s console is used may be very difficult to use when connected remotely with a cellular telephone. For example, text descriptions or icon variations easily understood using a large display may be indistinguishable on a small one. Differences in color used to distinguish, e.g., threshold crossings of variables are naturally not effectively discerned on a monochrome display. 
     One approach to the problems presented by differing display capabilities would be to use different representations of critical indicators to be monitored on different displays, with more complex (and possibly more complete) representations used for higher-capability displays. Such an approach may be disadvantageous, however, in requiring a user of multiple display screens to become familiar with multiple representations of the monitored indicators. Use of multiple representations may make it more difficult to develop a desirable intuitive feel for any one representation. It would therefore be desirable to develop a method and system of monitoring critical indicators which may be effectively used on displays having diverse sizes and capabilities. 
     SUMMARY OF THE INVENTION 
     The problems outlined above are in large part addressed by a method and system in which icons representing critical indicators are displayed in superposition with a reference shape. The reference shape is divided into “higher-interest” and “lower-interest” portions, such that display of an icon over the higher-interest portion of the reference shape indicates a higher-interest value of the corresponding variable. In the case of a system administration application, for example, display of an icon over the higher-interest portion may indicate that the value of the corresponding variable has crossed a threshold into a range associated with a performance problem for the system or network. For a stock-monitoring application, display of an icon over the higher-interest portion could indicate, for example, that the price of the corresponding stock has crossed a “buy” or “sell” threshold preset by the user. In the case of the horse-racing example mentioned above, display of an icon over the higher-interest portion may indicate, for example, that a corresponding race is currently underway, or that a particular horse corresponding to the icon has placed at or above a preset level (e.g., second place) in its most recent race. 
     The reference shape is preferably elongated horizontally, and an upper portion of the shape is typically designated as the higher-interest portion, while the lower portion of the shape is designated the lower-interest portion. In one preferred embodiment, the reference shape is an elongated oval. Multiple icons, corresponding to multiple monitored variables, may be displayed over the reference shape. Each monitored variable is preferably allocated a vertical “slice” of the reference shape, such that the position of the corresponding icon when the variable is in the higher-interest state is laterally aligned with (i.e., along the same vertical line as) the position of the icon when the variable is in the lower-interest state. In some embodiments, a single icon representing the present status of the corresponding variable is positioned over either the higher-interest or lower-interest portion of the reference shape. Alternatively, two icons may be used for each variable, where one is positioned over the higher-interest portion and the other over the lower-interest portion. In such an embodiment, the icon representing the present value of the variable is given a distinctive appearance, such as being displayed with a higher contrast. 
     Use of the reference shape to indicate the status (higher-interest or lower-interest) of a monitored variable is believed to confer several advantages. The relatively large size of the reference shape (it may be scaled to essentially fill a display, if desired) is believed to make the status of the monitored variables visible at a glance, even on a small display. Because the status is indicated by position of the icon, differences in individual icon characteristics such as color or shape, which may be difficult to discern on a small and/or monochrome display, need not be relied upon. Since detailed icon structures are therefore not necessary, the representation of the monitored variables may be implemented using a relatively simple reference shape and simple icon geometries (such as simple shapes). This simplicity may allow the representation to be scaled to small sizes without loss of information content. In this way, the same representation may be used on displays for diverse computational devices, freeing the user from the need to use different representations on different displays, and freeing application developers from the need to develop multiple representations. Cross-platform interoperability may therefore be enhanced. 
     In addition to providing a rapid indication of the status of a monitored variable, the representation described above may include a method of indicating that the status of the variable has changed, from higher-interest to lower-interest or vice versa. The status change may be indicated by changing the appearance of the icon corresponding to the present status of a monitored variable. For example, the icon may be made to blink, or to move back and forth. Such a change in appearance is typically implemented for a predetermined period of time following the change of status, where the time period may be set by an application developer and/or a user. Such an indication that the status of a variable has changed is believed to be advantageous in situations for which rapid action is required in response to changes in monitored variables. As in the case of other aspects of the display representation described above, this change in icon appearance is believed to be conveniently observed, even on low-capability displays. The time at which a status change occurs may also be stored and provided to a viewer through a GUI implementing the display representation described herein. In an embodiment, the time of the status change may be shown on the display screen during the time period of the above-described icon appearance change. Alternatively, the time may be displayed in response to a user selection of the icon corresponding to the present status of the variable. Display of the time at which a status change occurs may be important in, for example, allowing an assessment of the potential effects of the status change. 
     In some applications, it is desirable to know not just the time of the most recent status change of a variable, but a history of multiple status changes. Stock prices, for example, may cross a threshold value in different directions numerous times a day. The same is true of certain computer system and network quantities, depending on, for example, the degree of utilization of the system or network. As an example, a person providing technical support for a computer network may receive a report of a particular failure, but then not be able to locate a problem. A history of status changes of critical network indicators during the time elapsed since the failure could help in comparing the situation at the time of the failure and that at the time of the diagnosis attempt. In an embodiment of the methods described herein, the above-described representation of critical indicator status using a reference shape is combined with storage of information relating to each crossing of a monitored variable between its higher-interest and lower-interest ranges. The information may include, for example, the time and direction of each crossing, and/or a description of a particular event associated with the crossing. The stored information may then be displayed as a history of the status changes of a given monitored variable. Such a history is typically displayed in response to a user selection of the corresponding icon. 
     An embodiment of a system for transferring information within a client/server network includes a display controller operably coupled to a display screen. The display controller is adapted to display a reference shape on the display screen, as well as a superimposed present status icon corresponding to the present status of a monitored variable. The display controller is further adapted to position the present status icon over a first portion of the reference shape when the present value of the monitored variable is within a higher-interest range, or over a second portion of the reference shape when the present value of the variable is within a lower-interest range. The system may further include a storage medium operably coupled to the display controller, where the storage medium is adapted to store information relating to the higher-interest and lower-interest ranges. The display controller, storage medium and display screen may or may not all be associated with the same computational device. In an embodiment, the display controller and storage medium are associated with one device, while the display screen is on a different device. 
     In embodiments of the system, the display controller may be further adapted to change the appearance of the present status icon for a predetermined time interval after a crossing of the corresponding variable between the higher-interest range and lower-interest range has occurred. Alternatively or in addition, the display controller may be adapted to display information regarding the time of such a crossing, and the storage medium may be adapted to store this time-related information. In some embodiments, the display controller may be further adapted to display a history of status changes of the monitored variable, where the history includes a time of each crossing between the higher-interest and lower-interest range. In such an embodiment, the display controller may be further adapted to store this history information. 
     In addition to the method and system described above, a computer-usable carrier medium is contemplated herein. The carrier medium may be a storage medium, such as a magnetic or optical disk, a magnetic tape, or a memory. In addition, the carrier medium may be a transmission medium, such as a wire, cable, or wireless medium along which data or program instructions are transmitted, or a signal carrying the data or program instructions along such a wire, cable or wireless medium. The carrier medium may contain program instructions executable for carrying out embodiments of the methods described herein. Alternatively or in addition to such program instructions, the carrier medium may contain data used in implementing the methods described herein, such as data defining higher-interest and lower-interest ranges for variables, or time and direction data for crossings of a variable between these ranges. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings in which: 
     FIG. 1 is a block diagram illustrating an embodiment of a system for displaying information; 
     FIGS.  2 ( a )- 2 ( c ) illustrate embodiments of the information display described herein; 
     FIGS.  3 ( a )- 3 ( c ) illustrate exemplary reference shape and icon embodiments suitable for the information display methods described herein; 
     FIGS.  4 ( a )- 4 ( c ) illustrate embodiments of indicating when a monitored variable has crossed between its higher-interest and lower-interest ranges; 
     FIGS.  5 ( a )- 5 ( b ) illustrate embodiments of displaying a history of status changes of a monitored variable; and 
     FIG. 6 is a flow diagram illustrating an embodiment of a method for displaying information. 
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A block diagram illustrating an exemplary embodiment of a system which may be used to implement the methods described herein is shown in FIG.  1 . Computational device  10  includes processor  12 , display controller  14 , and storage medium  16 . Display controller  14  configures data for display on a display screen such as display screen  26 , and may provide an interface between computational device  10  and display screen  26 . Storage medium  16  may take many forms, such as volatile or nonvolatile memory, a magnetic disk such as a hard drive or floppy drive, an optical disk, and/or a magnetic tape. In the embodiment of FIG. 1, storage medium  16  includes variable range data  18 , crossing time data  20 , crossing history data  22  and program instructions  24 , also referred to as program executables. The program instructions may be stored as “executable files” in a direct access storage device such as a disk and loaded into memory during execution. Variable range data  18  identifies higher-interest and lower-interest ranges for the values of each variable to be monitored on the display screen. Crossing time data  20  typically includes the time at which the value of a variable has most recently crossed between its higher-interest and lower-interest ranges. Crossing history data  22  may include times for multiple range crossings of each variable, as well as the direction of each crossing (from higher-interest to lower-interest, or vice versa). Other information may also be included in crossing history data  22 , such as a value of the monitored variable at the time of the crossing, or information on an event associated with the crossing. Program instructions  24  may include various program instructions used to implement functions of computational device  10 , such as program instructions used to implement the methods described herein. 
     Transmission medium  28  may be used to connect computational device  10  to peripheral devices or networked devices. In the embodiment of FIG. 1, display controller  14  is connected to display screen  26  using medium  28 . Transmission medium  28  may include, for example, a wire, cable, circuit board trace, wireless transmission path, or a combination of these. Display screen  26  may be formed using various technologies, including liquid crystal display (LCD) technology, cathode ray tube (CRT) technology or projection technologies. Furthermore, display screen  26  may have any of the various sizes and capabilities typically found in displays on diverse computational devices. In some embodiments, display screen  26  may be directly connected to computational device  10 , as, e.g., a monitor or built-in display. Alternatively, display screen  26  may be associated with a different computational device than computational device  10 . In such an embodiment, display screen  26  may be associated with a separate display controller for that device (not shown), which may interact with display controller  14 . 
     In FIG.  1  and any other block diagrams appearing herein, the blocks are intended to represent functionality rather than specific structure. Implementation of the represented system using circuitry and/or software could involve combination of multiple blocks into a single circuit or device, or combination of multiple circuits and/or devices to realize the function of a block. For example, processor  12  and display controller  14  may be included on the same semiconductor chip, or display controller  14  may itself contain a processor. Furthermore, the system may include other elements not explicitly shown. For example, a computational device such as computational device  10  is typically associated with at least one input device such as a keyboard and/or pointing device (e.g., a mouse), and at least one output device such as a display or printer. 
     Exemplary representations for monitoring of critical indicators are shown in FIG.  2 . For example, an image which may appear on a display screen such as screen  26  of FIG. 1 is shown in FIG.  2 ( a ). The representation of FIG.  2 ( a ) includes reference shape  30  and present status icons  32 ,  34 ,  36  and  38 . In the embodiments of FIG. 2, reference shape  30  is an oval elongated in the horizontal direction, but other shapes may also be used, as discussed in more detail with reference to FIG. 3 below. Reference shape  30  provides a reference to the viewer for the positions of present status icons  32 - 38 . In particular, icons  32  and  38  are positioned over an upper portion of shape  30 , while icons  34  and  36  are positioned over the lower portion. The upper portion of the reference shape is typically designated the “higher-interest” portion. In such an embodiment, the representation of FIG.  2 ( a ) indicates that the variables corresponding to icons  32  and  38  are presently within their higher-interest ranges. The higher-interest and lower-interest ranges are specific to each variable being monitored. If, for example, icon  32  corresponds to space available on a particular disk associated with a computer system, a system administrator may wish to be alerted to a present value of this available space below some predetermined threshold value. A value below this threshold value could therefore be designated as being within the higher-interest range for this variable. In the case of an investor monitoring stock prices, the higher-interest range for a particular stock could be defined as either above or below a threshold value, depending, for example, on whether the investor were interested in an opportunity to sell or one to buy. The image in FIG.  2 ( a ) is believed to make clear at a glance that the variables corresponding to icons  32  and  38  are in their higher-interest ranges, while those corresponding to icons  34  and  36  are in their lower-interest ranges (assuming that the upper portion of shape  30  is the higher-interest portion). 
     In an alternative embodiment shown in FIG.  2 ( b ), alternative status icons  40 ,  42 ,  44  and  46  are displayed in addition to the reference shape and present status icons. The present and alternative status icons corresponding to a given variable are laterally aligned, such that the icons are positioned along the same perpendicular to a horizontal line bisecting reference shape  30 . The alternative status icons are positioned over the opposite portions of reference shape  30  as are their corresponding present status icons. These icons therefore correspond to an alternative status of the corresponding variable, or the status that the variable does not currently have. In the event of a change in status of a variable, the positions of the present status and alternative status icons corresponding to the variable are switched. Use of the alternative status icons may aid in delineating the particular “slice” of the reference shape allocated to a given variable, and may help to familiarize a viewer with the two possible status positions of an icon (higher-interest and lower-interest). The present status icons are in some way distinguished in appearance from their corresponding alternative status icons. In the embodiment of FIG.  2 ( b ), the present status icons are displayed with darker contrast (e.g., denser fill and/or solid rather than dashed lines). Other distinctions could also be used, however, such as making the present status icons have a different size or shape than the alternative status icons. 
     A partitioning of reference shape  30  corresponding to the embodiments of FIGS.  2 ( a ) and  2 ( b ) is shown in FIG.  2 ( c ). In a preferred embodiment, upper portion  48  and lower portion  50  of the reference shape are separated by the horizontal line bisecting the shape. The portions need not be halves of the shape in all embodiments, however. Upper portion  48  is typically designated the higher-interest portion, and lower portion  50  the lower-interest portion. This designation could be switched, although having the higher-interest portion on top is believed to be more intuitive for most applications. In the examples given hereinafter, the upper portion of a reference shape will be designated the higher-interest portion, unless specified otherwise. Sections  52  of shape  30 , separated by the vertical lines in FIG.  2 ( c ), are each reserved for icons corresponding to a single monitored variable. Although four sections are shown, many more sections for more monitored variables could be designated, depending on the relative sizes of the reference shape and the icons. 
     The representations shown in FIG. 2 represent merely exemplary embodiments, and many other embodiments are possible and contemplated. For example, the reference shape and/or icons shown in FIG. 2 could in some embodiments be formed from dashed lines rather than solid lines. In some embodiments, the icons could be positioned within the interior of reference shape  30 , rather than on the perimeter (as long as the icons remained positioned within the proper portion of the shape). Use of the perimeter is believed to be preferable, however, in that a greater visual distinction between the two variable states is observed. As another example, guide lines could be provided on the representations of FIGS.  2 ( a ) or  2 ( b ) in some embodiments. Such guide lines could delineate, for example, the boundary between the higher-interest and lower-interest portions of shape  30 , the boundaries between the sections (such as sections  52 ) reserved for each monitored variable, or the perpendiculars along which the higher-interest and lower-interest positions are aligned. 
     Some of the many embodiments of reference shapes and icon configurations which may be used in the display representation described herein are shown in FIG.  3 . As illustrated by FIG.  3 ( a ), the reference shape does not necessarily need to be a closed shape. A shape such as open-ended oval  54  may be used in some embodiments. The reference shape is preferably one that effectively guides the eye in distinguishing between higher-interest and lower-interest states of the monitored variables, but otherwise need not have any specific form. In the embodiment of FIG.  3 ( a ), present status icons  56  all have the same shape, although each corresponds to a different monitored variable. Using relatively few simple shapes for the icons may be beneficial in reducing the complexity of the representation, so that it may be more effectively scaled to fit small displays without loss of information. Whether identical icons or distinctive icons are used for the different variables, the graphical user interface may be configured to identify the variable corresponding to each icon upon a user request. For example, an identifying text or graphic could be displayed upon pointing to an icon using a pointing device such as a mouse, in a manner similar to use of a “mouseover” in the JavaScript language. The identifying information could alternatively be displayed in response to an actual “click” on (or selection of) the corresponding icon. 
     Shapes other than ovals may also be used for reference shapes, as illustrated by the embodiments of FIGS.  3 ( b ) and  3 ( c ). Rectangular reference shape  58  may be used in some embodiments, for example. Although the rectangular shape has similar symmetry to the oval shape of FIG. 2, it is believed that the oval shape may be more aesthetically pleasing and possibly less fatiguing to use. For example, if the reference shape is scaled to nearly fill a small rectangular display screen, the representation using the curved oval shape may be more easily distinguishable from the screen edges than one using a rectangular shape. The variation in height of the oval along its horizontal dimension may also aid the eye in matching the higher-interest and lower-interest icon positions corresponding to each variable, in that the matching positions share a vertical displacement (from the maximum height) as well as a lateral position which is different than that for an adjacent pair of icon positions. Such improved matching of the higher-interest and lower-interest positions for each variable may be increasingly important for representations containing a large number of monitored variables. Rectangles or other shapes may be suitable in some embodiments, however. 
     In some embodiments, the reference shape may not be vertically and/or horizontally symmetric. For example, reference shape  60  in FIG.  3 ( c ) is not vertically symmetric. In this embodiment, the higher-interest and lower-interest positions of an icon corresponding to a particular variable are not along a perpendicular to the horizontal line bisecting the reference shape, but rather along slanted lines  78 . A non-symmetric shape such as reference shape  60  may in some embodiments be useful in, for example, emphasizing the higher-interest portion of the shape over the lower-interest portion. Visible guide lines such as lines  78  would be more likely to be needed in such an embodiment, however. Another possible icon embodiment is also shown in FIG.  3 ( c ). Square icons  70 ,  72 ,  74  and  76  are partially “filled” to give a rough indication of the present value of the corresponding variable. For example, icon  70  appears to represent a variable currently having a relatively high value (as compared to its normal range), while icon  76  appears to represent a variable currently having a relatively low value. Both of these icons are in the higher-interest portion of the reference shape in this embodiment, indicating that the present value of each of the corresponding variables is within its higher-interest range. 
     In general, symmetric reference shapes and simple icon designs are believed to be most conducive to rapid determination of a variable&#39;s state and to scalability of the display to small sizes. As is partially illustrated by the embodiments of FIG. 3, however, many variations of reference shape and icon configuration may be used. Although the representations described herein do not rely upon color to indicate the status of a variable for reasons described above, color may of course be included if desired, possibly to make the display more aesthetically pleasing on screens which will support it. 
     Turning now to FIG. 4, exemplary embodiments are shown of display images which may result from the methods described herein of indicating a status change of a variable. In the embodiment of FIG.  4 ( a ), icons  80 ,  82 ,  84  and  86  are displayed with reference shape  30 . The short lines surrounding icons  82  and  86  are used in the figure to indicate that these icons are blinking on the display. The icons are caused to blink in this embodiment because they have recently crossed between the higher-interest and lower-interest portions of the reference shape. The variable corresponding to icon  82  has recently crossed from its lower-interest range to its higher-interest range, while that corresponding to icon  86  has recently crossed from its higher-interest range to its lower-interest range. The blinking is initiated upon the range crossing, and continued for a predetermined time interval, where the time interval may be set by, for example, a developer of an application using the display representation, or a viewer of the display. Other ways of changing an icon&#39;s appearance may be used instead of, or in addition to, the blinking shown in FIG.  4 ( a ). For example, an icon may be moved back and forth about its usual position, or the size of the icon could be alternately increased and decreased. In the embodiment of FIG.  4 ( a ), timestamps  88  and  90  are displayed in the vicinity of blinking icons  82  and  86 , respectively. Timestamp  88  shows the time at which the variable corresponding to icon  82  most recently crossed from its lower-interest to higher-interest range, while timestamp  90  shows the time at which the variable corresponding to icon  86  crossed from its higher-interest to lower-interest range. In this embodiment, the timestamps are displayed for the same time interval during which the icon appearance is changed, as part of an alert to the viewer that the status of the corresponding variable has changed. 
     Alternatively, a timestamp could be displayed only upon request by a viewer (or “user”), as illustrated in FIG.  4 ( b ). Pointer  92  may be moved across the display screen using a pointing device such as a mouse or trackball. Icon  80  underlying pointer  92  may be selected, typically by pushing a button on the pointing device. Timestamp  94 , indicating the most recent time at which the variable corresponding to icon  80  crossed from its higher-interest to lower-interest range, may be displayed in response to such a selection. The selection of an icon may therefore be considered a request by a viewer to see the corresponding timestamp of the corresponding variable&#39;s last status change. In some embodiments, simply positioning a pointer over an icon may be sufficient to cause display of the timestamp, without an actual selection of the icon being needed. In the embodiment of FIG.  4 ( b ), timestamps corresponding to icons  82  and  86  are not automatically displayed in response to the recent status changes of the corresponding variables. Timestamps for these icons may be viewed by user request in the same manner illustrated for icon  80 . 
     In order to allow other information relating to a monitored variable to be accessed in addition to timestamp information, selection of an icon may result in appearance of, for example, a menu bar, as shown in the embodiment of FIG.  4 ( c ). Menu bar  96  appears upon selection of icon  84  using pointer  92 . Various pieces of information regarding the variable corresponding to icon  84  are then available by selection with the pointer. A status change timestamp, similar to timestamps  88 ,  90  and  94  discussed above, may be chosen, as may a history of multiple recent status changes (discussed further below with reference to FIG.  5 ). Other information available may include, for example, the current value of the variable, an identification of the variable being monitored, or information regarding an event associated with the status change. 
     Exemplary embodiments of display of history information are shown in FIG.  5 . An example of a history display within the representation of FIG. 4 is shown in FIG.  5 ( a ). Pointer  92  is moved to overlie icon  86 , giving rise to the display of history  98 . In some embodiments, history  98  could display automatically (without a user&#39;s pointing to or selecting an icon), for example, during the time interval following a status change of a variable. Such an embodiment is believed to typically require excessive display space, however. In another embodiment, history  98  could be displayed when pointer  92  is positioned over icon  86 . History  98  could also display only upon selection of icon  86 , or through selection and then use of a menu bar such as bar  96  of FIG.  4 ( c ). In the embodiment of FIG. 5, history  98  includes variable identification  100 , threshold value identification  102 , time information  104 , direction information  106 , variable value information  105 , and percentage filled information  107 . The variable corresponding to icon  86  is identified as “Space Available on Disk C”, and the threshold value of this variable is given as 100 megabytes (MB). The range higher than 100 MB would therefore reasonably be considered the lower-interest range, while that lower than 100 MB would be the higher-interest range (since a problem could occur if the disk space gets too low). In some embodiments, definitions of the higher-interest and lower-interest ranges could also be given in the history. 
     Time information  104  includes timestamps for the most recent crossings of the variable between its higher-interest and lower-interest ranges. The most recent of the timestamps corresponds to timestamp  90  for the same variable shown in FIG.  4 ( a ). Direction information  106  includes the direction of each of the crossings, from the higher-interest range to the lower-interest range, or vice versa. The number of crossings appropriately included in the history may depend on the nature of the variable being monitored. As for many parameters associated with the display representations described herein, this number of crossings could be set or changed by, for example, an application developer or a user of the display. In some embodiments, the crossing direction information in the history could be given in terms of the actual variable units (e.g., from greater disk space to lesser, or vice versa), rather than in terms of higher and lower-interest ranges. In the embodiment of FIG.  5 ( a ), the history also includes variable value information  105 , which is the value of the available disk space at the time of each threshold crossing (the value moved to). Percentage filled information  107  gives the percentage filling of Disk C corresponding to each value. In this example, Disk C has a one gigabyte capacity. 
     A different embodiment of history display, used with a representation such as that of FIG.  2 ( b ), is shown in FIG.  5 ( b ). Pointer  92  is positioned over present value icon  38 , resulting in the display of history  99 . As discussed above the display could be in response to, for example, a selection (“clicking”) of the icon with the pointer, simply moving the pointer over the icon, or selecting a portion of a menu bar. History  99  is similar to history  98  of FIG.  5 ( a ) except that only crossings of the variable into its higher-interest range are included. In the embodiment of FIG.  5 ( b ), selection of other icons in the higher-interest portion of shape  30  (e.g., icons  32 ,  42  or  44 ) would result in similar history displays in which the crossings into the higher-interest range of the variable corresponding to the icon are included. Selection of (or possibly pointing to) an icon in the lower-interest portion of shape  30 , on the other hand, may result in a different history display. Pointer  93  is positioned over alternative status icon  46 , resulting in display of history  101 . History  101  is similar to histories  98  and  99 , except that only crossings of the variable corresponding to icon  46  into its lower-interest range are included. In this embodiment, similar histories could also be displayed for the variables corresponding to icons  40 ,  34  and  36 . Other information not shown in FIG. 5 could be included in history displays such as  98 ,  99  and  101 . For example, a description of an event associated with each crossing could be included. The event could be one which may have given rise to the threshold crossing. In the example of FIG. 5, such an event could be the saving of a particular file to Disk C by a particular application program. 
     A flow diagram illustrating an embodiment of a method for displaying information is shown in FIG.  6 . The method of FIG. 6 may be performed using a system such as that shown in FIG. 1, and may be part of an application program running on a computational device such as device  10  of FIG.  1 . In the embodiment of FIG. 6, a continuous loop is performed in which each of the variables to be monitored is polled in turn and the display appropriately updated. If this method were applied, for example, to the set of variables corresponding to the display of FIG.  2 ( a ), the position of icon  32  would be updated on the display screen, then icon  34 , then  36 , then  38 , then  32  again, and so forth. To begin the display of monitored variables, a reference shape is displayed on a display screen (box  108 ). This is typically done by a display controller such as display controller  14  of FIG. 1, coupled to a display screen such as screen  26 . The present value of the first monitored variable is then compared to its predetermined higher-interest and lower-interest ranges (box  110 ). The present value of the variable may be obtained by, for example, processor  12  of FIG.  1 . The present value may, for example, be provided by an application running on computational device  10 , obtained from another device networked to device  10  (using a transmission medium similar to medium  28 ), or possibly input by a user of the computational device. Information regarding the predetermined higher-interest and lower-interest ranges for the variable may be included in variable range data  18  of FIG.  1 . The ranges may be defined by persons including an application developer or a viewer of the display screen, and may be established by defining a threshold value of the variable at the boundary between the higher-interest and lower-interest ranges. 
     The comparison of the present value of the monitored variable to the higher-interest and lower-interest ranges, typically performed by a processor such as processor  12  (or possibly by display controller  14 , especially if it contains a processor), is used to determine whether the monitored variable is within the higher-interest range (decision box  112  of FIG.  6 ). If so, a present status icon is displayed (typically by a display controller) over the higher-interest portion of the reference shape, in a lateral position reserved for the corresponding variable (box  114 ). If the value of the monitored variable is not within its higher-interest range, the present status icon is instead displayed over the lower-interest portion of the reference shape (box  116 ). In embodiments for which alternative status icons are used (decision box  118 ), an alternative status icon is displayed over the opposite portion of the reference shape as the present status icon corresponding to the same variable (box  120 ). 
     If a first pass through the flow diagram of FIG. 6 is being made for a particular variable (decision box  122 ), then no change of the variable status can be detected during that pass. An example of a way to determine whether it is the first pass through the method is to reserve a set of storage locations to store the previous status of each variable. These storage locations could be initialized at the beginning of the method flow (e.g., before step  108 ), with a value indicating the initial pass through the method. The storage location could then be checked during step  122 , and if the initial value were present (rather than, e.g., “high-interest” or “low-interest”) a determination made that the first pass was in progress. If a first pass is not being made, it is determined whether the present status of the variable has changed as compared to the previous pass (decision box  124 ). Such a determination could be made by comparing the present status of the variable to the previous status, stored in the location discussed above with reference to step  122 . The previous status location could then be updated later in the sequence, such as subsequent to step  126 . If there has been a change in status, the time and direction of the change (current time, and whether the change is from high-interest to low-interest or vice versa) are stored (box  126 ). Alternatively or in addition, other information such as the value of the variable or a description of an event associated with the change in status could be stored. In the embodiment of FIG. 6, the appearance of the present status icon is also altered during a time interval following the change in status (box  128 ). This altering of appearance may include making the icon blink, or other changes in appearance, some of which are described above in the discussion of FIG.  4 . If there has not been a change in status, but the time period following a previous change in status has not expired (box  130 ), the alteration of the icon appearance is continued. 
     If timestamp or history information is requested by a user (decision box  132 ), the requested information is displayed (box  134 ). Such a user request may include, for example, a positioning of a pointing device over an icon, selection of an icon, and/or selection of a choice within a menu bar. The present value of the next monitored variable is then compared to its range data (box  136 ), and the loop is started again. Multiple variations of the method of FIG. 6 are possible and contemplated. In some embodiments, for example, display of timestamp and/or history information could be done automatically during the time period for which the appearance of the present status icon is altered. 
     Program instructions, such as instructions  24  of FIG. 1, implementing methods such as that illustrated by FIG. 6 may be transmitted over or stored on a carrier medium. The carrier medium may be a transmission medium such as a wire, cable, or wireless transmission link, or a signal traveling along such a wire, cable or link. The carrier medium may also be a storage medium, such as a volatile or non-volatile memory (e.g., read-only memory or random access memory), a magnetic or optical disk, or a magnetic tape. 
     It will be appreciated by those skilled in the art having the benefit of this disclosure that this invention is believed to provide a system and method for allowing critical indicators to be monitored on a display screen. Furthermore, it is also to be understood that the form of the invention shown and described is to be taken as exemplary, presently preferred embodiments. Various modifications and changes may be made without departing from the spirit and scope of the invention as set forth in the claims. For example, the system and methods described herein may be implemented using many combinations of hardware and/or software, and at one or more of many different levels of hardware and/or software, as is the case with many computer-related applications. It is intended that the following claims be interpreted to embrace all such modifications and changes.