Syntactical structure (3)
Language compatibility command structure (semantics and syntax) should correspond to the terminology and data organisation familiar or natural to the user. [EXAMPLE the rules for natural language syntax (e.g. English, French, etc) are applied in designing a query language]
Command arguments command arguments should be easy for the user to specify and to relate to the commands that they modify. [NOTE in some cases, it may be appropriate to represent arguments as names rather than single letters] command elements linkage - the command dialogue should be structured so that the relationship between the command phrase elements is clear. arguments format - if appropriate to the task, keyword format (parameter designated by argument identifiers that precede them) should be used rather than positional formats (parameter designated by their sequential position in the argument string following the command). [EXAMPLE (keyword format): change shape=round colour=red size=4] [EXAMPLE (positional format): change round red 4] placement of optional argument - if keyword format is used, optional arguments should be placed at the end of the argument list. Separation of arguments - (a) if BLANK spaces are allowed, a variable number of blanks should be allowed between command elements; (b) if other separators are used, a simple standard symbol should be used consistently. [EXAMPLE using the comma (,) in the command phrase “print fileA,fileB,fileC”]