The Semantic Data Charter (SDC4) is an open specification for creating self-describing, semantically rich data models that work seamlessly across systems and languages.

Make data trustworthy, interoperable, and permanent.

We believe the foundation of data trust should be:

• Open - Built on international standards, not proprietary lock-in
• Accessible - Language-agnostic, enabling global collaboration
• Governed - Built-in lineage and provenance for accountability
• Permanent - CUID-based immutability for long-term data integrity

1. Enforce Governance - Built-in lineage and provenance tracking
2. Embed Meaning - Semantic interoperability via RDF/OWL
3. Mandate Quality - Validation rules and quality constraints

Think of it as: "Protocol Buffers with semantics and governance"

SDC4 combines:

• Structure (like Protocol Buffers) - XML Schema 1.1 for data types and constraints
• Semantics (like RDF/OWL) - Meaning and relationships
• Validation (like SHACL) - Quality rules and business logic
• Governance - Lineage, provenance, and audit trails
• Packaging - Self-contained, queryable data packages

Result: Data that is self-describing, semantically rich, and audit-ready.

• ✅ Language Agnostic - Model in Portuguese, French, Japanese, Spanish, etc.
• ✅ Standards-Based - Built on 16+ W3C, ISO, and IETF standards
• ✅ AI Governance - Built-in lineage for trustworthy, explainable AI
• ✅ Namespace Versioning - CUIDs for immutable, evolvable components
• ✅ Multi-Format Export - RDF, OWL, SHACL, FHIR, GraphQL, JSON, GQL

• Enterprise Data Integration - Canonical models for multi-system environments
• AI Governance - Data packages with automatic lineage for trustworthy AI
• Cross-Border Exchange - Semantic interoperability without translation
• Regulatory Compliance - Built-in audit trails and provenance
• Legacy Modernization - Bridge between old and new systems

• SDCRM v4.0.0 - Reference model, schemas, and specification
• sdc-xml2graph v4.0.0 - Transform SDC4 XML to knowledge graphs (Q1-2026)
• SDCObsidianTemplate v4.0.0 - Markdown templates

• sdcvalidator (Python) v4.0.1 - Python validation library
• sdcvalidatorJS (TypeScript) v4.0.0 - JavaScript/TypeScript implementation

• SDCStudio v4.0.0 - Web application for model generation (proprietary)

All SDC4 projects use 4.x.x versioning where the MAJOR version (4) represents the SDC generation.

SDC4 is not a new idea—it's the commercialization of 15+ years of validated research:

Evolution Timeline:

• 2000-2009: FreePM/TORCH (open source healthcare applications)
• 2009-2017: MLHIM (430 commits, 165+ citations, healthcare focus)
• 2012-2025: S3Model (1,586 commits, domain-agnostic generalization)
• 2025-present: SDC4 (commercial production platform)

Academic Validation:

• 12+ peer-reviewed papers (AMIA, JCI, JAMA, IEEE/ACM)
• 165+ citations on Google Scholar
• Proven in healthcare, research, and enterprise contexts

Verification: Historical Archive - 4.2GB, 76,313 files, full Git history (2013-2025)

SDC4 is built on international standards:

W3C Standards:

• XML Schema 1.1 (structure)
• RDF 1.1 (semantics)
• OWL 2 (ontologies)
• SPARQL 1.1 (queries)
• SHACL (validation)

ISO Standards:

• ISO 11179 (metadata registries)
• ISO 20022 (financial messaging)
• ISO/IEC 21838 (top-level ontologies)
• ISO 21090 (healthcare data types)

IETF Standards:

• RFC 3986 (URIs)
• RFC 8259 (JSON)
• And more...

Total: 16+ international standards

pip install sdcvalidator

from sdcvalidator import SDC4Validator

# Create validator with schema
validator = SDC4Validator('schema.xsd')

# Validate and recover
recovered = validator.validate_with_recovery('data.xml')

# Generate validation report
report = validator.validateAndReport('data.xml')
print(f"Errors: {report.errorCount}")

git clone https://github.com/SemanticDataCharter/SDCRM.git
cd SDCRM
# See sdc4/schemas/sdc4.xsd (source of truth)
# See sdc4/specification/sdc4-specification.md

We welcome contributions to all SDC4 projects!

• Code - Implement features, fix bugs, improve performance
• Documentation - Write guides, improve examples, translate content
• Testing - Write tests, report bugs, verify fixes
• Use Cases - Share how you're using SDC4
• Feedback - Suggest improvements, discuss architecture

1. Read the Contributing Guidelines
2. Check the Code of Conduct
3. Review the Security Policy
4. Find a project that interests you
5. Open an issue or PR

Each repository has its own CONTRIBUTING.md and CLAUDE.md files with specific guidance for that project.

We take security seriously. See our Security Policy for:

• Vulnerability reporting
• Security best practices
• Response timeline

Report vulnerabilities: security@axius-sdc.com

• Website: https://semanticdatacharter.com
• Specification: sdc4-specification.md
• PyPI Package: sdcvalidator
• Historical Archive: GitHub
• AI Instructions: ai.txt

Developer: Axius SDC, Inc. Contact: contact@axius-sdc.com License: Apache 2.0 (specification and open source tools)

Founders:

• Timothy W. Cook - Founder & CEO
• Dr. Luciana Tricai Cavalini, PhD - Co-Founder & Partner
• Dr. Nikki Shaw, PhD - Co-Founder & Partner

Team: International (US, Canada, Brazil), 40+ years combined experience

• Website: semanticdatacharter.com
• Company: axius-sdc.com
• LinkedIn: Axius SDC
• Email: contact@axius-sdc.com

• SDC4 Specification: Apache 2.0
• Open Source Libraries: Apache 2.0
• Trademarks: "Semantic Data Charter" and "SDC4" owned by Axius SDC, Inc.

Building the future of trusted data, one semantic model at a time. 🚀

Last Updated: November 2025