When communication is top-down in the form of directives, it is recognised as

Top-down communication flowing as directives from higher to lower levels is recognised as official communication, the formal channel that carries authority through the hierarchy.

It moves along the sanctioned line of command, so instructions descend from those in charge to those who must act.

Calling it lateral misreads it, since lateral flow runs sideways between peers on the same level, not downward.

Naming it collateral confuses it with a side or supporting channel rather than the recognised chain of command.

Treating it as external is wrong, because external communication reaches outward to audiences beyond the organisation.

Downward directive flow is a defining feature of formal organisational communication and its authority structure.