Model Documentation is the comprehensive and detailed technical record required by the EU AI Act that provides a complete account of a high-risk AI system's design, development, operational parameters, and performance characteristics, serving as the primary evidence for conformity assessment and regulatory oversight.

This documentation transforms the AI system from an opaque software artifact into a transparent, auditable product. It acts as the "single source of truth" for the system, capturing not just what it does, but how and why it was built that way. Required elements go beyond code comments to include the rationale behind design choices, the characteristics of the training data, the results of rigorous testing, and the system's known limitations. This living document is essential for regulators to verify compliance, for deployers to understand proper use, and for the provider's own teams to facilitate maintenance, updates, and incident investigation.

The EU AI Act mandates that model documentation encompass several critical domains:

System Specifications: A clear statement of the system's intended purpose, functional requirements, architecture, and hardware/software dependencies.

Data Documentation: Detailed information on the datasets used for training, validation, and testing, including their sources, scope, preprocessing steps, and an assessment of quality, representativeness, and potential biases.

Development & Training Process: A description of the model selection, training methodologies, techniques used for bias mitigation and robustness, and the computational resources utilized.

Performance Evaluation Results: Comprehensive reporting of all testing outcomes against predefined metrics for accuracy, robustness, cybersecurity, and performance across relevant sub-populations to assess fairness.

Risk Management & Instructions: Documentation of identified risks, the mitigation measures implemented, and clear, comprehensive instructions for the deployer on safe and compliant use.

Regulatory Context: The requirement for detailed technical documentation is codified in Article 11 of the EU AI Act and further specified in Annex IV. This documentation is a core component of the conformity assessment (Annexes VI and VII) and must be kept up-to-date and made available to national authorities for a period of ten years after the system is placed on the market.

Compliance & Accountability Artifact: Well-maintained model documentation is the cornerstone of an organization's defense in demonstrating "accountability by design." It enables efficient audits, supports serious incident investigations, and is indispensable for managing substantial modifications. Inadequate documentation is itself a violation of the Act and severely hinders an organization's ability to prove compliance.

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