Guidance

1. User guidance cannot be regarded as a special kind of dialogue technique; this design issue was recognized as important to develop a separate pan.

2. Whatever dialogue technique a user may apply, supporting information provided by prompts or feedback as well as assistance for recovering from errors will always be required enabling the user to continue the dialogue.

3. Although error prevention is always appropriate, the user's effort to undertake remedial actions needs specific system support, for example as undo function, history function.

4. In addition, the conditions for automatic error correction are described. Requirements also address the design of on-line help, which may be induced by the user or the system.

5. The standard provides criteria to guide the design of system-initiated versus user-initiated help.

Feedback

1. Providing default options and appropriate feedback is likely to the important part of the design of any selection mechanism.

2. Default options are particularly desirable when one option is selected much more often than any of the others.

3. Under these circumstances search and selection operations can be made more efficient by highlighting the default option and preselecting it by having its identifier automatically displayed on the command line or having the pointer automatically located at the default option.

4. Regardless of the selection mechanism, the system should provide instructions regarding the context of the menu, how a response should be made and feedback indicating:

(1) which options are selectable,

(2) when an option is under the pointer and, therefore, can be selected (assuming a pointer is used),

(3) which options have been selected so far, and

(4) the end of the selection process.

1. These feedback characteristics are particularly important in highly interactive applications where the options on pop-up or pull-down menus are likely to be lists of commands and/or arguments.

2. Two techniques are commonly used to prevent users from selecting inappropriate choices. One approach is to gray-out or otherwise mark those options that don't make sense in a given context.

3. The unselect ability of the faded option is reinforced when it is under the pointer since it will not become highlighted.

4. The second approach is to dynamically alter the visibility of the options, i.e. inappropriate options simply disappear from the screen.

5. It is difficult to offer guidelines with respect to these two techniques since their relative benefits and costs have not been explored empirically.