The descriptors

Catenator defines multiple descriptors:

Descriptor	Specifies
domain	the vocabulary and rules governing the system
model	the data structures the system operates on
component	the discrete, reusable pieces the system is made of
service	the capabilities the system exposes or consumes
operation	the individual operations the system performs
actor	who or what interacts with the system
event	what the system must respond to
rule	the constraints the system must enforce
process	the workflows the system executes
integration	the system's boundaries with external systems
utility	what the system does, for whom, and to what end
risk	what can go wrong, how likely, and who bears it

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What each descriptor covers

Name	Description
domain	names the vocabulary the system operates in and the rules that govern it before any code is written. A pharmacy domain carries different constraints than a SaaS platform. The domain descriptor makes those constraints explicit and referenceable across the spec.
model	describes the data structures the system operates on — what objects exist, what attributes they carry, what states they can be in. A model is not a database schema. It is the conceptual shape of the system's objects before any implementation decision is made.
component	names the discrete, reusable pieces the system is made of. A component has a boundary, a contract, and a set of responsibilities. It does not describe implementation — it describes what the piece does and what it exposes.
service	describes capabilities the system exposes to the outside or consumes from outside. A service has a contract — what it receives, what it returns, what it guarantees. Internal logic is not part of the service descriptor.
operation	describes the individual operations the system performs — the atomic actions that change state, produce output, or trigger events. An operation is initiated by an actor, operates on a model, and produces a result.
actor	names who or what interacts with the system. Actors can be people, external systems, or automated processes. An actor has a role, a set of permitted operations, and a context in which it operates.
event	describes what the system must respond to — things that happen that require a reaction. Events can originate inside the system or outside it. An event triggers a process, an operation, or a state transition.
rule	names the constraints the system must enforce. Rules can be internal — business logic, validation, state machine constraints — or external — regulatory requirements, contractual obligations, platform policies. Rules are not embedded in operations. They are declared separately and referenced.
process	describes the workflows the system executes — the sequences through which objects move, actors interact, and events are handled. A process connects operations, actors, and events into a coherent flow.
integration	describes the system's boundaries with external systems — what it depends on, what depends on it, and the contracts at those boundaries. An integration names the external system, the protocol, the data exchanged, and the failure modes.
utility	describes what the system does, for whom, and to what end — its purpose from the outside. Utility is not a feature list. It is the statement of value the system produces for the actors who depend on it.
risk	names what can go wrong, how likely it is, and who bears the consequence. Risk is not an afterthought. It is a first-class descriptor that shapes decisions across every other part of the spec.

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Using descriptors

No descriptor is mandatory. A spec can use one descriptor or all of them — depending on what the system requires and what the agent needs to proceed.

A minimal spec might declare only utility and domain. A complete spec activates all thirteen. Most real specs live between these extremes — using the descriptors the system's complexity requires, leaving the rest implicit or deferred.

Some descriptors have subtypes that carry distinct requirements. Subtypes are defined in the descriptor reference.

The descriptors are not a checklist. They are a vocabulary. Use what the system requires.

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