Pd Documentation 2: "2.6.4. inlets and lists
The leftmost connection point at the top of most objects represents the object itself. Any other dark rectangle is a separate object called an 'inlet' although in Pd there are 4 individual inlet classes. The class of the inlet determines which messages it will take: symbol, float, or other; and the inlet forwards the message either to the object proper or to some proxy, usually one that the object creates for the occasion."
