WPI Worcester Polytechnic Institute

Computer Science Department

Mayhew's Book (chapt. 7)

Designing Command Languages

Command Language Semantics

  • Balance power and simplicity (richness and minimality, respectively) according to user needs.

Command Language Syntax

  • Provide consistency in syntax.

  • Use an action-object syntax.

  • Avoid arbitrary use of punctuation.

  • Avoid positional grammars.

  • A command language syntax should be natural and mnemonic.

  • Allow defaulting of optional parameters.

  • Avoid frequent use of shift or control keys.

Command Language Lexicon

  • Design command names to be hierarchical, congruent, specific, familiar, consistent in grammatical form, and discriminable.

  • Use user jargon and avoid computer jargon.

  • Use a simple, consistent rule for command name abbreviations.

  • Allow full command names and emphasize them in training, even if abbreviations are allowed.

Command Language Interaction

  • Locate the command line at the bottom of the screen or window, unless it is clear that the user's eyes will be elsewhere at input time.

  • Provide interactive support through defaults, command editing, intelligent interpretation, type-ahead, and feedback.

  • Provide memory aids such as on-line quick reference and prompting.

  • Provide function keys for high-frequency commands.

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dcb [at] cs.wpi.edu / Fri Feb 28 22:31:27 EST 1997