One port of one component, written "COMP/PORT". PORT is matched against the port names Issie gives that component type, ignoring case and surrounding space, and falls back to being read as a port index. The fallback is not a convenience: many component types - gates, inputs, outputs, wire labels, constants, bus selects, splitters - have no port names at all, so an index is the only way to refer to them. PORT may be left off entirely ("A" rather than "A/0") when the component has exactly one port in the direction wanted, which covers Inputs, Outputs and most single-output components.