Appendix B — Glossary

Terms in this glossary name recurring design distinctions rather than new S7 APIs. Each definition links to its principal treatment in the book.

Aggregate root

The object boundary that sees a complete consistency unit and can enforce relationships among its contained values. See the checking ladder.

Canonical equality

Equality after applying documented normalization rules, without requiring exact R representation identity. See identity and equality.

Contextual preparation

A named operation that combines an intrinsically valid value with external data, metadata, resources, or authority and returns a value recording what was resolved. See contextual preparation.

Domain equality

Equality defined by meaning in the problem domain rather than exact storage representation. See round-trip equivalence.

Invariant

A condition that must remain true for a value or consistency boundary throughout its supported lifecycle. See retained knowledge.

Operation contract

The meaning, accepted concepts, result, failure policy, and laws shared by every implementation of an operation. See defining operations.

Property contract

The class, shape, cardinality, presence policy, default behavior, and intrinsic constraints attached to one property position. See the property inventory.

Projection

A deliberate representation derived from an authoritative model, such as a schema, serializer output, interface description, or documentation page. See schema architectures.

Reference owner

An object with shared identity or a live lifecycle whose aliases must observe the same evolving state. See the lifecycle policies.

Semantic class

A nominal class that preserves a domain concept independently so it can travel through the program or participate in dispatch. See the semantic carriers.

Snapshot

A value representing a fact at a point in time, often with a public policy that forbids revision. See the lifecycle policies.

Sum type

A representation of alternatives in which a value is exactly one of several meaningful variants. See alternatives and variants.

Wire representation

The serialized form exchanged with another system, distinct from the program’s semantic domain model. See documents and schemas.