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Blockchain LabTHE VENTURE STUDIO

LibraryMarkets2018Design paperCorpus record

Non-Fungible Token Standard

ERC-721. William Entriken, Dieter Shirley, Jacob Evans and Nastassia Sachs.

Each token id has an owner. Transfer moves that id. An optional metadata URI points at a description. The standard does not say the description is true, or that the object exists off-chain.

A reading of the public document. Not a copy of it, and not a claim about a later network that reused the name.

A title-transfer pitch should say what a court would look at: the token, the URI, or a registry elsewhere.

The five-minute read

The defect

ERC-20 balances are interchangeable. A deed, a ticket, or a particular object is not.

The rule

Each token id has an owner. Transfer moves that id. An optional metadata URI points at a description. The standard does not say the description is true, or that the object exists off-chain.

How it is put together

Uniqueness is the id, inside one contract. The owner is an address. Metadata is a pointer, not a proof.

Where the claim stops

The token is not the object.

One action, walked through

  1. Mint an id to an owner.
  2. Transfer the id.
  3. A marketplace approves an operator and transfers when a sale settles.
  4. What does this id correspond to off-chain?

The argument, unpacked

Why it is still on the desk

A title-transfer pitch should say what a court would look at: the token, the URI, or a registry elsewhere.

After the text

Markets standardised on this interface. The legal object, if any, is outside the EIP.

What has to be true

  • The token is not the object.
  • Two contracts can both have an id 1.
  • Metadata can change or vanish if the URI is a server.

What happened after the paper

Markets standardised on this interface. The legal object, if any, is outside the EIP.

What to check before you use the idea

  • What does this id correspond to off-chain?
  • Can the metadata URI be changed, and by whom?
  • Is the operator approval unlimited?

Terms

Token id
The integer that identifies one asset inside this contract.
Operator
An address allowed to move any of an owner's tokens in this contract.

The problem the paper names

ERC-20 balances are interchangeable. A deed, a ticket, or a particular object is not.

What the design proposes

  • Uniqueness is the id, inside one contract.
  • The owner is an address.
  • Metadata is a pointer, not a proof.

How the mechanism is specified

  • Mint an id to an owner.
  • Transfer the id.
  • A marketplace approves an operator and transfers when a sale settles.

What this page does not treat as proven

  • The token is not the object.
  • Two contracts can both have an id 1.
  • Metadata can change or vanish if the URI is a server.

Why a venture studio still reads it

A title-transfer pitch should say what a court would look at: the token, the URI, or a registry elsewhere.

This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.

Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.