Glossary

This glossary provides a best-effort capture of acronyms and terms used throughout the UCP specification. New entries should be added in alphabetical order within their respective category.

Note: Even with this glossary, it is preferred that the first usage of an acronym in each specification Markdown file spells out the full term (e.g., "Payment Card Industry Data Security Standard (PCI-DSS)").

Protocol

Term	Acronym	Definition
Agent Payments Protocol	AP2	An open protocol designed to enable AI agents to securely interoperate and complete payments autonomously. UCP leverages AP2 for secure payment mandates.
Agent2Agent Protocol	A2A	An open standard for secure, collaborative communication between diverse AI agents. UCP can use A2A as a transport layer.
Capability	-	A standalone core feature that a business supports (e.g., Checkout, Identity Linking). Capabilities are the fundamental "verbs" of UCP.
Credential Provider	CP	A trusted entity (like a digital wallet) responsible for securely managing and executing the user's payment and identity credentials.
Extension	-	An optional capability that augments another capability via the extends field. Extensions appear in ucp.capabilities[] alongside core capabilities.
Model Context Protocol	MCP	A protocol standardizing how AI models connect to external data and tools. UCP capabilities map 1:1 to MCP tools.
Profile	-	A JSON document hosted by businesses and platforms at a well-known URI, declaring their identity, supported capabilities, and endpoints.
Universal Commerce Protocol	UCP	The standard defined in this document, enabling interoperability between commerce entities via standardized capabilities and discovery.

Commerce

Term	Acronym	Definition
Business	-	The entity selling goods or services. In UCP, they act as the Merchant of Record (MoR), retaining financial liability and ownership of the order.
Merchant of Record	MoR	The legal entity responsible for the sale, including financial liability and order ownership.
Payment Service Provider	PSP	The financial infrastructure provider that processes payments, authorizations, and settlements on behalf of the business.
Platform	-	The consumer-facing surface (AI agent, app, website) acting on behalf of the user to discover businesses and facilitate commerce.

Payments

Term	Acronym	Definition
Card Verification Value	CVV	The 3 or 4 digit security code on payment cards used to verify card-not-present transactions.
Payment Card Industry Data Security Standard	PCI-DSS	A set of security standards designed to ensure that all companies that accept, process, store or transmit credit card information maintain a secure environment.
Primary Account Number	PAN	The unique payment card number (typically 13-19 digits) that identifies the card issuer and cardholder account.
Strong Customer Authentication	SCA	A requirement under PSD2 that payment service providers apply multi-factor authentication for electronic payments.
3D Secure	3DS	A protocol designed to add an additional security layer for online credit and debit card transactions through cardholder authentication.

Compliance & Regulatory

Term	Acronym	Definition
California Consumer Privacy Act	CCPA	A state statute intended to enhance privacy rights and consumer protection for residents of California, United States.
General Data Protection Regulation	GDPR	A regulation in EU law on data protection and privacy in the European Union and the European Economic Area.
Know Your Customer	KYC	The process of verifying the identity of clients to prevent fraud, money laundering, and terrorist financing.

Standards & Specifications

Term	Acronym	Definition
International Organization for Standardization	ISO	An international standard-setting body composed of representatives from various national standards organizations. Referenced in UCP for country codes (ISO 3166-1), currency codes (ISO 4217), and date formats (ISO 8601).
Verifiable Digital Credential	VDC	An Issuer-signed credential (set of claims) whose authenticity can be verified cryptographically. Used in UCP for secure payment authorizations.