[Functionalism is] a distinction between kinds of duties. - James D. Mooney

The informative phase refers to those things which authority should know in framing its decisions; the advisory, to the actual counsel based on such information; the supervisory, to both preceding phases as applied to all the details of execution. The point is that the line represents the authority of man; the staff, the authority of ideas. The staff is purely an auxiliary service. Its function is to be informative and advisory with respect to both plans and their execution. This is implicit in the word "staff" which is something to support or lean upon but without authority to decide or initiate.

The third and effectuating principle of the entire scalar process is Functional Definition.

In organization it means the graduation of duties, not according to differentiated functions, for this involves another and distinct principle of organization, but simply according to degrees of authority and corresponding responsibility.