Enter as an interface discipline

Cheung's Enter calculus treats quantum names as access rights and destructive readout as an operation that consumes the measured names while returning a classical result CheungEnter,CheungI. The introductory philosophy distinguishes destructive readout, quantum recovery, implementation, and geometric identification CheungPhil.

We retain that discipline. Agreement of record probabilities is weaker than agreement of instruments; a channel alone does not specify a thermal machine; and naming a register “clock” does not identify it with a continuum coordinate. We adopt finite Born and projective-update semantics. We do not rederive the separate measurement-characterization theorem from an abbreviated hypothesis list.

The instrument terminology is consistent with the operational framework of Davies and Lewis and with finite completely positive maps DaviesLewis,Choi. Every channel identity used below is proved directly.