Interface
An interface is a relation or channel through which causal exchange crosses a specified system boundary.
Boundary and interface should not be collapsed.
For a persistent organization, an interface is also where selective boundary control becomes operational: flows may be rate-limited, transformed, authenticated, routed, admitted, or rejected. The interface implements the crossing; the boundary specifies the inside–outside distinction and the conditions under which that crossing matters.
A boundary distinguishes inside from outside for a chosen question.
An interface specifies where and how relevant exchange occurs across that distinction.
Interfaces can transmit:
- matter;
- energy;
- information;
- authority;
- signals;
- other causal influence.
Expanding an interface can increase both opportunity and exposure. Whether an interface is beneficial, harmful, permitted, or forbidden is a separate evaluation layer from the fact that it is causally operative.