As CUls have replaced command languages, intricate syntax has given way
to relatively simple direct manipulations applied to visual representations of
objects and actions. The emphasis is now on the visual display of user-task
objects and actions. For example, a collection of stock-market portfolios might
be represented by leather folders with icons of engraved share certificates; likewise, actions might be represented by trash cans for deletion, or shelf icons to
represent destinations for portfolio copying. Of course, there are syntactic
aspects of direct manipulation, such as knowing whether to drag the file to the
trash can or vice versa, but the amount of syntax is small and can be thought of
as being at the lowest level of the interface actions. Even syntactic forms such as
double-clicking, mouse-down-and-wait, or gestures seem simple compared to
the pages of grammars for early command languages.