C.3.5:3.4 - K3 — Up-to-Iso

Intent. The kind’s governed criterion is invariant under a declared isomorphism or equivalence notion.

Cues. Structural equivalence, rather than individual identity, is load-bearing in the signature and receiving use.

Non-example. A class whose candidate identity matters beyond the declared structure is not K3.

Planning. Require explicit equivalence witnesses and receiver acceptance. High CL^k is justified only when the obtaining bridge and its assertion demonstrate preservation of the relevant equivalence structure.