---
title: "MPP request with no currency — x402 defect class mpp-currency-unnamed"
description: "MPP request with no currency (mpp-currency-unnamed), an x402 defect class: The request names its currency: ISO 4217 lowercase for fiat, a token contract address for chains, or the method's own convention. Detectable by an unpaid probe. A client cannot resolve what the amount is denominated in; a wallet that assumes settles in the wrong asset or refuses."
canonical: "https://scvd.store/defects/mpp-currency-unnamed"
url: "https://scvd.store/defects/mpp-currency-unnamed"
term_code: "mpp-currency-unnamed"
defined_in: "https://scvd.store/defects"
data: "https://scvd.store/defects.json"
vocabulary_version: "22"
license: "https://creativecommons.org/licenses/by/4.0/"
---

# MPP request with no currency

`mpp-currency-unnamed` — an x402 defect class.

**Asserts:** The request names its currency: ISO 4217 lowercase for fiat, a token contract address for chains, or the method's own convention.

**Costs:** A client cannot resolve what the amount is denominated in; a wallet that assumes settles in the wrong asset or refuses.

**Detectable:** unpaid — a free probe can see it

**Falsified by:** The request carrying a non-empty currency at the stated moment.

**How an operator clears it:** Name the currency on every request in the form the method draft specifies, and keep it beside the amount in one object so they cannot drift.

**What a buyer does:** Do not sign for an amount with no currency: you cannot know what you are paying in. Refuse, and say which field was missing.

**Our signal:** `mpp-currency-named`

---

Vocabulary v22, CC BY 4.0. Every class: https://scvd.store/defects. Machine-readable, with falsifiers and cross-instrument mappings: https://scvd.store/defects.json.

A class describes a property of one endpoint at one moment and never accumulates into a judgment on an operator.