Section 9 of 83
8. Interface Contract Model
Stable section ID: S05-CON-005-SECTION-9 · 15 content blocks
The Interface Contract Model is the formal mechanism through which System05 defines the relationship between participating components.
An Interface Contract shall establish the conditions that must be satisfied for two or more entities to connect, communicate, operate, disconnect, and remain compatible throughout their intended lifecycle.
The contract shall define the identity and version of the interface; the participating roles; physical geometry; datum systems; alignment features; tolerances; engagement sequence; locking method; release method; access requirements; operating limits; transferred forces, energy, materials, data, and commands; environmental conditions; safety functions; inspection provisions; and required evidence.
The contract shall distinguish between mandatory requirements, optional capabilities, conditional capabilities, prohibited behaviors, and manufacturer-declared extensions.
Mandatory requirements shall be satisfied by every compliant implementation. Optional capabilities may be provided without preventing basic interoperability. Conditional capabilities become mandatory when a declared configuration, profile, environment, or operating mode applies. Prohibited behaviors identify actions that could create unsafe states, damage, ambiguity, or incompatibility. Extensions may introduce new functionality provided they do not violate the base contract.
Every Interface Contract shall define preconditions for engagement. Preconditions may include compatible versions, acceptable physical condition, verified identity, isolation of hazardous energy, environmental suitability, authentication, available capacity, correct orientation, and authorization to proceed.
The contract shall define the engagement process and the evidence required to confirm successful connection. Visual proximity or mechanical contact alone shall not constitute verified engagement where additional structural, electrical, fluid, digital, or safety conditions must be satisfied.
Operational states shall be defined, including disconnected, discovered, aligned, partially engaged, mechanically secured, sealed, energized, authenticated, commissioned, operational, degraded, isolated, faulted, under maintenance, and decommissioned, as applicable.
Permitted and prohibited transitions between states shall be specified. A component shall not transition directly into an operational state unless all required intermediate verifications have been completed.
The contract shall define operating limits and capability negotiation rules. Components shall operate according to the mutually compatible portion of their declared capabilities. No component may assume that the other side supports an optional capability unless that capability has been positively identified and accepted.
Fault behavior shall form part of the contract. Detection, notification, containment, isolation, safe-state transition, emergency override, diagnostic access, and recovery requirements shall be declared before the interface is approved for use.
The contract shall define disconnection conditions and sequence. Stored energy, structural load, fluid pressure, hazardous materials, active commands, data synchronization, and lifecycle records shall be safely managed before release.
Every Interface Contract shall exist in coordinated human-readable and machine-readable forms. The human-readable form shall provide authoritative engineering understanding. The machine-readable form shall enable automated selection, design validation, compatibility checking, manufacturing, assembly, commissioning, operation, maintenance, and robotic interaction.
Contract compliance shall be verified through defined evidence and shall remain traceable throughout the Digital Thread. Any modification affecting the contract shall initiate version control, compatibility assessment, validation, and—where required—recertification.
The Interface Contract Model transforms a connection from an assumed physical relationship into an explicit, testable, traceable, and governable engineering agreement. It is the primary mechanism through which System05 protects interoperability while allowing products, manufacturers, materials, technologies, and regional implementations to evolve independently.