Extensions

Shows which vCon extension drafts exist, what token each one uses, and where its data sits in a vCon, so you can add structured data without breaking readers.

The core draft, draft-ietf-vcon-vcon-core-04, keeps the container small. Anything beyond the core parties, dialog, analysis and attachment fields belongs in an extension: a separate draft that defines new parameters, attachment purpose values or analysis type values, and registers a token for them.

How extensions are declared

Two top-level arrays carry extension names (core-04 Sections 4.1.3 and 4.1.4):

• extensions lists every extension whose parameters appear in the vCon. It SHOULD be present when any are used.

• critical lists the extensions a reader must support to interpret the vCon correctly. A reader that finds a name it does not support in critical MUST NOT process the vCon except to reject it or report it.

Core-04 calls an extension Compatible when an unaware reader can ignore it safely, and Incompatible when it changes meaning. Only Incompatible extensions, or ones whose draft says so, go in critical. All the extensions below are Compatible.

A top-level fragment for a vCon carrying an agent trace that downstream systems must honor, plus a lawful basis attachment:

{
  "extensions": ["agent_session", "lawful_basis"],
  "critical": ["agent_session"]
}

There is no must_understand field. must_support is the 0.3.0 name for critical. See the field reference for every renamed field.

Available extensions

Extension	Token	Where its data lives	Draft
Lawful Basis	lawful_basis	attachments[] with purpose: "lawful_basis"	draft-howe-vcon-lawful-basis-02
WTF Transcription	wtf_transcription	analysis[] with type: "wtf_transcription"	draft-howe-vcon-wtf-extension-02
Agent Session	agent_session	agent parties[], analysis[] with type: "agent_trace", attachments[] with agent_* purposes	draft-howe-vcon-agent-session-00
SIP Signaling	sip-signaling	sip_* party and dialog parameters, attachments[] with sip-* and stir-* purposes	draft-howe-vcon-sip-signaling-00
Contact Center	CC	party role, contact_list; dialog campaign, interaction_type, interaction_id, skill	draft-ietf-vcon-cc-extension-02
Provenance	provenance	a provenance object on an analysis or dialog entry	draft-howe-vcon-provenance-00
Lifecycle	none	events on a SCITT transparency service, outside the vCon	draft-howe-vcon-lifecycle-01

Lifecycle is listed here because it is usually read alongside Lawful Basis, but it defines no extension token and adds nothing to the vCon itself.

Every attachment uses purpose, never type. That includes lawful_basis.

Related work outside the vCon WG

draft-howe-sipcore-mcp-extension is a SIP protocol extension that carries MCP payloads inside SIP sessions. It adds nothing to a vCon.

draft-birkholz-verifiable-agent-conversations defines Verifiable Agent Conversation records. It is not a vCon extension; the Agent Session extension embeds its records.

Writing a new extension

Check first whether your data fits as an analysis entry (anything derived from the conversation) or an attachment with a new purpose (anything supplied alongside it). Most data does, and needs no new draft.

If you need new parameters, write an Internet-Draft. Core-04 Section 2.5 says what it must contain: the extension name and whether it goes in extensions, critical or both; each new parameter and where it appears; compatibility and incompatibility considerations; and privacy and integrity considerations. Register the token in the vCon Extensions Names Registry (core-04 Section 6.4). Bring it to the IETF VCON working group.