Description

Quick reference for terms and abbreviations used in ERC-8004 Offchain Standards

Abbreviations

A

A2A - Agent-to-Agent Protocol
Communication protocol enabling direct agent-to-agent interactions and collaborations.
Specification

Arweave (AR) - Permanent decentralized storage network
Uses ar:// URI scheme

C

CAIP - Chain Agnostic Improvement Proposal
Standards for blockchain-agnostic identifiers

CAIP-2 - Blockchain ID format (namespace:chainId)
Example: eip155:1 for Ethereum Mainnet

CAIP-10 - Account address format (namespace:chainId:address)
Example: eip155:1:0x742d35...

CID - Content Identifier
Unique hash-based identifier used in IPFS
Example: bafkreiabc... (CIDv1)

E

EIP - Ethereum Improvement Proposal
Process for proposing standards to Ethereum ecosystem

ERC - Ethereum Request for Comments
Standards track within EIP process (e.g., ERC-20, ERC-721, ERC-8004)

ERC-8004 - Trustless Agents Standard
NFT-based standard for AI agent identity, reputation, and validation

G

Groth16 - Type of zkSNARK proof system
Widely used zero-knowledge proof construction, efficient verification

I

IANA - Internet Assigned Numbers Authority
Organization that maintains official MIME type registry

IPFS - InterPlanetary File System
Content-addressed, peer-to-peer file system
Uses ipfs:// URI scheme

ISO 8601 - International date and time format standard
Example: 2025-12-21T14:30:00Z

J

JSON - JavaScript Object Notation
Text-based data format used for all offchain metadata

K

Keccak-256 - Cryptographic hash function
Used for content hashing in Ethereum (produces bytes32 output)

M

MCP - Model Context Protocol
Protocol for AI agents to expose tools, prompts, and resources
Specification

MIME Type - Multipurpose Internet Mail Extensions
Standard for indicating file type (e.g., application/json, image/png)

N

NFT - Non-Fungible Token
Unique token standard (ERC-721), used for agent identity in ERC-8004

O

OASF - Open Agent Skills Framework
Taxonomy for categorizing agent capabilities and domains.
Specification

OASF Domain - High-level field of operation
Categories like finance_and_business, healthcare_and_medicine, technology_and_engineering.
See: OASF Domain Taxonomy

OASF Skill - Specific capability an agent possesses
Hierarchical paths like analytical_skills/data_analysis, communication_skills/content_creation.
See: OASF Skills Taxonomy

P

PLONK - Type of zkSNARK proof system
More flexible than Groth16, supports universal setup

R

RFC 2119 - Key words for requirement levels
Defines MUST, SHOULD, MAY, etc. for specification documents

S

SemVer - Semantic Versioning
Version numbering scheme (MAJOR.MINOR.PATCH)

Services (Agent Metadata Field) - Top-level array field in agent metadata (Jan 2026+)
The official field name for the array of service endpoints in agent metadata JSON. Replaces legacy endpoints field name. Each service object contains name, endpoint, and optional fields like version, skills, etc.

• Current: "services": [...] ✅ Recommended (EIP-8004 Jan 2026)
• Legacy: "endpoints": [...] ⚠️ Deprecated but still supported
• Note: Different from the singular endpoint property within each service object, and different from the endpoint field in feedback data.
  See: Agent Metadata Standard - Field Migration

STARK - Scalable Transparent Argument of Knowledge
Type of zero-knowledge proof, post-quantum secure

T

TEE - Trusted Execution Environment
Hardware-based secure computation (e.g., Intel SGX, ARM TrustZone)

U

URI - Uniform Resource Identifier
Generic identifier for resources (includes URLs)
Schemes: https://, ipfs://, ar://, data:

URL - Uniform Resource Locator
Subset of URI using http:// or https:// schemes

UTC - Coordinated Universal Time
Standard time zone (offset +00:00), required for all timestamps

X

x402 - Payment protocol for AI agents
Protocol for agent payment proofs referenced in feedback records

Z

zkML - Zero-Knowledge Machine Learning
Techniques for proving ML model execution without revealing model weights

zkSNARK - Zero-Knowledge Succinct Non-Interactive Argument of Knowledge
Cryptographic proof system enabling verification without revealing inputs
Types include Groth16, PLONK, STARK, Halo2

Key Terms

AgentURI

Offchain metadata URI referenced by ERC-8004 Identity Registry NFTs. Points to JSON containing agent identity, services, and capabilities.

See: Agent Metadata Standard

Attachment Pattern

Standardized schema for including evidence files in feedback and validation records. Defines fields like name, uri, mimeType, size.

See: Attachment Pattern Standard

Base Sepolia

Ethereum Layer 2 testnet (chainId: 84532). Used extensively in 8004scan production data.

Compatibility Levels

Three-level system for classifying offchain data formats:

• Level 1: ERC-8004 Standard (recommended)
• Level 2: Known Custom Formats (recognized)
• Level 3: Unknown Formats (stored as-is)

See: Validation Standard - Format Compatibility

Data URI

URI scheme for embedding data inline: data:[mediatype][;base64],<data>

Example: data:application/json;base64,eyJuYW1lI...

Feedback Authorization (Deprecated in v1.1)

⚠️ DEPRECATED: This mechanism was removed in v1.1 (January 2026).

Two-step process for creating feedback:

1. Client requests permission via agent endpoint
2. Agent provides signature (feedbackAuth) authorizing feedback

v1.1: Anyone can submit feedback directly without pre-authorization. Spam protection relies on off-chain filtering.

See: Feedback Standard

Identity Registry

ERC-8004 smart contract managing agent NFTs and metadata URIs. Core component for agent registration.

Normative vs Non-normative

Normative: Defines requirements (MUST/SHOULD/MAY)
Non-normative: Provides informative guidance, examples, or rationale

Marked with: > **Non-normative**: ...

Offchain Data

JSON metadata stored off-blockchain (IPFS, HTTPS) and referenced by URIs in smart contracts.

Contrasts with onchain data: data stored directly in contract state.

Parse Status

Classification of how well offchain data conforms to standards:

• success - Perfect compliance
• warning - Minor issues, still usable
• known_custom - Recognized custom format
• unknown - Unrecognized format

Reputation Registry

ERC-8004 smart contract managing feedback records and reputation signals (values) for agents.

Validation Registry

ERC-8004 smart contract managing validation requests and responses (proofs, attestations).

Validation Type

Category of validation method:

• crypto-economic - Economic incentive based
• tee-attestation - Hardware-secured proof
• zkml-proof - Zero-knowledge ML proof

See: Validation Standard

Protocol References

MCP (Model Context Protocol)

Current Version: 2025-06-18
Specification: https://modelcontextprotocol.io/

Standard for AI agents to expose:

• Tools: Callable functions
• Prompts: Pre-defined prompt templates
• Resources: Data sources and context

A2A (Agent-to-Agent)

Current Version: 0.3.0
Specification: https://a2a.to/

Protocol for agent discovery, capability negotiation, and communication.

OASF (Open Agent Skills Framework)

Current Version: v0.8.0
Repository: https://github.com/agntcy/oasf/

Hierarchical taxonomy for agent:

• Skills: What agents can do (e.g., analytical_skills/data_analysis)
• Domains: What fields they operate in (e.g., finance_and_business)

x402

Payment protocol for AI agents. Enables proof of payment in feedback records.

Fields:

• fromAddress, toAddress (CAIP-10)
• txHash, amount, currency
• protocol: "x402"

Chain Identifiers

Common chain IDs using CAIP-2 format:

Blockchain	CAIP-2 Format	Chain ID
Ethereum Mainnet	eip155:1	1
Sepolia Testnet	eip155:11155111	11155111
Base Mainnet	eip155:8453	8453
Base Sepolia	eip155:84532	84532
Polygon PoS	eip155:137	137
Arbitrum One	eip155:42161	42161
Optimism	eip155:10	10

MIME Types

Common MIME types used in attachment patterns:

File Type	MIME Type
JSON	application/json
PDF	application/pdf
PNG	image/png
JPEG	image/jpeg
SVG	image/svg+xml
Plain Text	text/plain
CSV	text/csv
MP4 Video	video/mp4
ZIP Archive	application/zip

Custom formats: application/x-<format> (e.g., application/x-groth16-proof)

External References

• EIP-8004: https://eips.ethereum.org/EIPS/eip-8004
• RFC 2119: https://www.rfc-editor.org/rfc/rfc2119
• CAIP-2: https://github.com/ChainAgnostic/CAIPs/blob/main/CAIPs/caip-2.md
• CAIP-10: https://github.com/ChainAgnostic/CAIPs/blob/main/CAIPs/caip-10.md
• ISO 8601: https://www.iso.org/iso-8601-date-and-time-format.html