3. Structural Model

The structural model defines the required composition of an Application under chkpt. These structural elements ensure that each execution is deterministic, reviewable, and aligned with the certified workflow version authorised by the adopting organisation. chkpt does not prescribe representation formats or implementation details; it specifies the structural requirements that must be satisfied for an execution to be recognised under this specification.

3.1 Application Structure

An Application is the complete record of a single execution of a certified workflow. It consists of declared inputs, execution behaviour, declared results, and an evidence record. All elements must be structurally valid and consistent with the workflow version bound to the execution. Applications must be self‑contained and sufficient for institutional review. The conceptual basis for Applications is introduced in the Conceptual Model.

3.2 Declared Inputs

Declared inputs represent the information provided to the workflow at the start of execution. They must be explicitly defined, structurally valid, and complete. chkpt requires that declared inputs be immutable for the duration of the execution and that they conform to the input schema defined by the certified workflow. Declared inputs form part of the evidence obligations described in the Evidence Model.

3.3 Execution Behaviour

Execution behaviour describes the deterministic process by which chkpt applies the certified workflow to the declared inputs. It includes all intermediate steps, transformations, and state transitions required to produce the declared results. Execution behaviour must remain within the admissible behaviour boundaries defined by the workflow and enforced by chkpt. These behavioural constraints are detailed in the Execution Model.

3.4 Declared Results

Declared results represent the final outputs produced by the workflow. They must be explicitly defined, structurally valid, and consistent with the workflow’s specification. Declared results must be deterministically derived from the declared inputs and execution behaviour. Any deviation constitutes a failure condition under this specification.

3.5 Evidence Record

The evidence record contains the information required to review and reconstruct the execution. It includes declared inputs, declared results, relevant intermediate state information where required, and metadata linking the execution to the workflow and execution versions. Evidence must be complete, tamper‑resistant, and sufficient for institutional oversight. Evidence obligations are defined in detail in the Evidence Model.

3.6 Version Bindings

Each Application must bind to a specific workflow version and a specific execution version. Workflow versions are defined by the adopting organisation’s governance model. Execution versions identify the behaviour of the chkpt substrate itself. Both bindings must be recorded in the evidence record to ensure traceability and reviewability. Versioning rules are described in Versioning.