12. The PCT Namespace Registry

12.1 Purpose and authority

The PCT Namespace Registry is the authoritative record of all registered extension namespace prefixes in the PCT ecosystem. It is maintained by DPG Labs as the authoring organisation of this specification.

The registry exists to prevent namespace collisions, establish clear ownership and accountability for each namespace, and ensure that verifiers and implementers can identify the authoritative definition of any extension claim they encounter. Without a registry, two organisations could independently define x-fintech: with conflicting semantics, creating ambiguity that undermines the reliability of PCT verification.

Registration is required for any organisation wishing to publish an extension namespace for use by third parties. An organisation may use unregistered namespaces internally, but must not publish or promote unregistered namespaces for external adoption. Verifiers encountering an unregistered namespace must treat it as unverified and flag the PCT for human review rather than failing silently.

12.2 Namespace prefix format

All extension namespace prefixes must conform to the following format:

x-{label}:

Where {label} is a short, lowercase, alphanumeric identifier with no spaces or special characters other than hyphens. Examples: x-ccpa:, x-lgpd:, x-uk-nhs:, x-psd2:.

The following prefixes are reserved by DPG Labs and may not be registered by third parties:

• x-hipaa:
• x-dora:
• x-duaa:
• x-pecr:
• x-ai-act:
• x-pct: (reserved for future core extensions)

12.3 Registration tiers

The registry operates on two tiers.

Tier 1 — Open Registration. Available at no cost to individuals, academic institutions, non-profit organisations, open source projects, and regulatory bodies. Tier 1 registrations are listed in the public registry with full documentation and are eligible for community review and promotion to core.

Tier 2 — Commercial Registration. Required for commercial organisations registering namespaces for use in products or services. Tier 2 registrations carry an annual registration fee, are listed in the public registry with full documentation, and are eligible for community review and promotion to core. Commercial registrants receive a verified badge in the registry.

Fee structures for Tier 2 registration are published separately at pct.thedpg.com/registry and are reviewed annually.

12.4 Registration requirements

An application to register a namespace must include the following:

Field	Type	Required	Description
namespace_prefix	string	REQUIRED	The proposed prefix in x-{label}: format.
registrant_name	string	REQUIRED	The full legal name of the registering organisation or individual.
registrant_contact	string (email)	REQUIRED	A stable contact address for the registrant.
regulatory_framework	string	REQUIRED	The regulatory framework, standard, or domain the namespace addresses.
jurisdiction	string	REQUIRED	The jurisdiction(s) to which the framework applies.
documentation_url	string (URI)	REQUIRED	A publicly accessible URL where the full namespace field definitions are documented.
fields	array of object	REQUIRED	A summary list of the fields defined within the namespace, each with a name, type, and description.
version	string	REQUIRED	The version of the namespace definition being registered. Must follow semantic versioning (e.g. 1.0.0).
tier	enum	REQUIRED	The registration tier. Values: open, commercial.
licence	string	OPTIONAL	The licence under which the namespace definition is published.

12.5 Registration process

Applications are submitted to registry@pct.thedpg.com or via the web form at pct.thedpg.com/registry/apply.

DPG Labs will review each application within 14 working days and will either approve the registration, request clarification, or reject the application with reasons. Grounds for rejection include conflict with an existing registration, conflict with the core schema field names, insufficient documentation, or failure to meet the format requirements of Section 12.2.

Approved registrations are published in the PCT Namespace Registry within 5 working days of approval. The registry is publicly available at pct.thedpg.com/registry and is also published as a machine-readable JSON file in the PCT specification GitHub repository at registry/namespaces.json.

12.6 Registrant obligations

Registrants are responsible for:

• Maintaining the accuracy of the documentation at the registered documentation_url.
• Notifying DPG Labs of any material changes to the namespace definition by submitting an updated registration.
• Renewing commercial registrations annually and maintaining payment of applicable fees.
• Ensuring that implementations of their namespace are consistent with the registered field definitions.

DPG Labs reserves the right to suspend or revoke a registration where a registrant fails to meet these obligations, where the namespace is found to conflict with the core schema, or where the registered documentation is found to be materially misleading.

12.7 Dispute resolution

Where two parties claim entitlement to the same namespace prefix, DPG Labs will adjudicate based on the date of application, the quality and completeness of the documentation, and the legitimacy of the claimed regulatory basis. DPG Labs' decision is final. Parties may appeal in writing within 30 days of a decision.

12.8 The registry record format

Each entry in the public registry is a JSON object conforming to the following structure:

{
  "namespace_prefix": "x-ccpa",
  "registrant_name": "Example Organisation",
  "registrant_contact": "pct@example.org",
  "regulatory_framework": "California Consumer Privacy Act / CPRA",
  "jurisdiction": "US-CA",
  "documentation_url": "https://example.org/pct/x-ccpa",
  "version": "1.0.0",
  "tier": "open",
  "registration_date": "2026-06-01",
  "status": "active",
  "fields": [
    {
      "name": "opt_out_flag",
      "type": "boolean",
      "description": "Indicates whether the data subject has exercised their right to opt out of sale or sharing of personal information."
    },
    {
      "name": "sensitive_pi_flag",
      "type": "boolean",
      "description": "Indicates whether the data includes sensitive personal information as defined under CPRA Section 1798.121."
    }
  ]
}

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