ITU-T Z 322-1988 CAPABILITIES OF VISUAL DISPLAY TERMINALS《直观显示终端的性能》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 : TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!.G13-!#().%G0G0,!.5!%#!0!“),)4)%3G0G0/ easily tracked as it is moved through the display; does not interfere with the reading of the symbol that it marks; should not be so distracting as to impair the searc

2、h for unrelated information displayed elsewhere on thescreen; should be of a form that is unique and reserved for that purpose only; should be stable in respect to the position to which it is addressed until it is readdressed elsewhere as aresult of user or system action.2.3 Screen partitioning defi

3、nitionThe following definitions describe the physical partitioning of the VDT screen.2.3.1 Visible displayThe visible display is the entire physical screen of a VDT (see Figure 1/Z.322).2.3.2 Border areaThe border area is that part of a visible display which is physically unavailable for displaying

4、or entering data(see Figure 1/Z.322).2.3.3 Display areaThe display area is that part of a visible display which is available for displaying or entering data (seeFigure 1/Z.322).2 Fascicle X.7 - Rec. Z.3222.3.4 Window and window areaThe display area can contain one or more windows. A window contains

5、a collection of related information. Awindow can consist of one window area or can be partitioned into window areas.The different characteristics and operations specifying windows and window areas depend both on the systemtype and on the physical capabilities of the terminal.2.3.4.1 Window definitio

6、nA window is a collection of one or more window areas which can occupy a part of the display area (sometimesthe entire display area) and it is used for entering and/or displaying data. The collection depends on the application. Awindow is dedicated to an application. More than one window per applica

7、tion can be present at the same time on thedisplay area.2.3.4.2 Window characteristicsThe main characteristics of a window are: its name: allowing it to be identified; its location: relation to the other windows in the display area. Windows are displayed independently ofeach other. Windows can appea

8、r superimposed one on top of another or located side by side. When awindow is located on top, it can hide a window or windows that are below it; the list of window areas it can contain; its size: its size expressed as height and width can vary; its state: a window can be “interactive”, or “not inter

9、active”. Information entry can be performed onlywhen the window is “interactive”; its visibility: a window is visible when it appears totally or partially on the screen. It can be partially visibleeither because it is overlapped by another window or because a part of the window is outside the displa

10、yarea; its limits: when it is visible, the limits of a visible part of a window must be obvious to the user; the application it is dedicated to.2.3.4.3 Window area definitionA window area is a named part of a window that is dedicated for a specific purpose depending upon theapplication.2.3.4.4 Windo

11、w area characteristicsThe main characteristics of a window area are: its name: allowing it to be identified; the purpose related to it;Fascicle X.7 - Rec. Z.322 3 its presence state: a window area can be “present”, or “not present”. If a window area is “not present”, itcan not be seen on the screen

12、whatever the position of the window it belongs to; its position in the window: the relative location of the window areas in a window should be fixed. Thislocation can only be modified by changing the presence state of other window area(s); its size: its size expressed as height and width may vary; i

13、ts visibility: when a window area is present, it can appear or not appear on the screen depending whetherthe part of the window it belongs to is visible or not; its limits: when it is visible, the limits of a window area must be obvious to the user; its text management: scrolling can be available in

14、 a window area.2.3.4.5 General rules for the display of windows and window areasA window can appear anywhere on the screen totally or partially in a non-restrictive manner.Windows and window areas need not be displayed in all systems or in all applications or all the time in a givensystem.The limits

15、 of windows and window areas must be unambiguously clear to the user. The techniques that may beused to achieve this include, but are not limited to the following: lines and boxes; inverse video; background colour. This use of colour should be distinguished from the use of colour as a highlightingte

16、chnique where colour should be used in combination with other techniques.Some examples of screens illustrating the use of windows and window areas are given in Figures 2/Z.322 to5/Z.322. In these figures, windows are outlined by double-line boundaries while the boundaries between window areasare dep

17、icted by single lines. Lines and boxes are used simply as a concrete example that can be produced easily inprint.2.3.5 Field2.3.5.1 Field definitionA field is a part of a window (sometimes the entire window area), which is used for entering or displayinginformation.2.3.5.2 Field characteristicsThe m

18、ost important characteristics, which may vary in time, are:a) its position within the window area;b) its size;c) its type: for entering information (input field): accessible for writing by user and system (e.g., default value); for displaying information (output field): inaccessible for writing by u

19、ser.The limits of an input field must be obvious to the user. There may be one or several fields within one windowarea (see Figure 6/Z.322).4 Fascicle X.7 - Rec. Z.3222.4 Physical characteristicsFor further study.Fascicle X.7 - Rec. Z.322 52.5 Video attributesVideo attributes are used to emphasize c

20、ertain important information, e.g., a title, a message, a chosen item, inorder to attract the attention of the user. Video attributes work on the characters of the information shown within anentire window or window area, a part of a window or window area, an entire field or within just a part of the

21、 field.The following video attributes may be provided singularly or in combination:2.5.1 LuminanceFor further study.Information can be displayed in different levels of luminance.2.5.2 ColourInformation can be displayed in different colours.2.5.3 FlashingInformation can be displayed alternately as no

22、rmal characters and as spaces in the prevailing backgroundcolour.2.5.4 UnderlineInformation can be displayed with underlined characters.2.5.5 SizeInformation can be displayed in different character sizes.2.5.6 FontInformation can be displayed in different fonts, e.g., italics, bold.2.5.7 Inverse vid

23、eoInformation can be displayed by inverting the image of the characters, such as going from light characters on adark background to dark characters on a light background.2.5.8 ConcealmentInformation can be displayed as space characters, e.g., secret parts of a password.3 Other output devicesFor furt

24、her study.4 Keyboard characteristicsFor further study.5 Other input devicesFor further study.6 Transmission characteristicsThere are two fundamental transmission mechanisms commonly employed and referred to as “character mode”and “block mode”.If a terminal uses character mode transmission, each and

25、every character input at the keyboard is sent to thecontrolling processor one at a time. Thus, as is the case with the syntax of Recommendation Z.315, if certain regularkeys have special meanings ascribed to them e.g., ; or !, then they can act as specific triggers to the controlling softwarewhich t

26、hen performs some process on the preceding information in accordance with the given syntax rules.6 Fascicle X.7 - Rec. Z.322If the same terminal uses block mode transmission, all of the regular typewriter keys and some of the specialpurpose keys only have an effect local to the terminal, i.e. the in

27、formation input goes into the “memory” of the terminaland onto the screen normally, but not to the controlling processor. The implication is, obviously, that special actionsassigned to these keys do not get processed until an explicit “send” action is made. A “send” action by the user is onlyrequire

28、d when information is to be moved from the terminal to the host processor.The important point for the purposes of these Recommendations is that the use of a “send” key is not explicitlyshown at any time. It is recommended that systems that employ “block mode” transmission either convey very explicit

29、instruction on when a “send” action is required of the user or are designed to be able to accept and respond intelligentlyto incomplete input, i.e. “send” can be used by the user at any point without a fundamental disruption of the dialogue.As far as possible this will shield the user from the effec

30、ts of the transmission mode employed.7 Control functionsControl functions are those functions related to the man-machine interface that are applied by the userindependently while in a dialogue with the system functions. Control functions have no direct impact on the systemfunctions. Control function

31、s are subdivided into cursor control functions and interface control functions.7.1 Cursor control functionsA cursor is generally used as an indicator of the position where an action will take place, such as a characterbeing written on the screen either by the system or by the user. Cursor control fu

32、nctions do not directly affect theoverall system state, but assist users in selecting data entry fields, editing fields, etc.Examples include:a) Home position of the cursorHere “home” means a position in the display area to which the cursor can be consistently moved, from anyposition, by a single ke

33、ystroke. The actual position in the display area which represents “home” may varyaccording to the activity being performed and the current layout of the display area.b) Movement control of the cursorAssuming that the VDT used supports direct cursor addressing, the following types of cursor movement

34、arepossible:i) by the system, andii) by the user via cursor control functions. General cursor control functions independent of dialogue are: one line up; one line down; one place left; one place right.Ideally, cursor movement should be easy to accomplish by means of a single, dedicated key for each

35、function.Shifted characters should be avoided. If a cursor positioning control key is used, it should repeat when held down.Cursor movement may also be controlled by other input devices, e.g., light pen, trackball, mouse or joystick.When cursor positioning is incremental by discrete steps, the step

36、size of cursor movement should be consistentin both right and left directions and both up and down directions. However, the cursor may bypass inaccessible fields.When character size is variable on the display, incremental cursor positioning should have a variable step sizecorresponding to the curren

37、tly selected character size.7.2 Interface control functionsFunctions of this class are used to force specific actions relating to the interface. They are invoked by variousmeans, including pressing dedicated control keys.Examples of man-machine interface control functions include, but are not limite

38、d to: send (other words for the same function are “transmit” and “enter”) see 6; editing control functions (insert character, insert line, replace character, etc.); capitals lock (the condition where letters are input as capitals only); select different font see 2.5.6; select different character size see 2.5.5.