Dated SIU 0.0014Settlement / USDCIndex print / Weekly · SignedMethod / Versioned

Touchstone Assay publishes Dated SIU.

The benchmark price of AI inference work.

One SIU is a fixed quantity of AI work: a versioned benchmark basket of inference tasks completed at a defined quality threshold.

A measurement standard · not a currency · nothing for sale

Dated SIU

0.0014

Publication date
2026-08-22
Status
PROVISIONAL
View the full series

A falling price is normal — one SIU always buys the same work.

The problem

Intelligence has no common unit of account.

Quoted per token

Per token

Input, output and reasoning tokens vary by tokenizer and model behavior.

Quoted per task

Per task

A nominal task says nothing about whether the result met a common quality bar.

Quoted per outcome

Per outcome

Outcome contracts bundle intelligence, risk and workflow into one incomparable price.

Every model prices in incompatible tokens — different tokenizers, different verbosity, reasoning tokens billed as output — so neither a finance team nor an AI agent can compare what a unit of intelligence actually costs.

The analogy

The commodity, the grade, the settlement.

Oil never got its own currency. It got a benchmark grade — Dated Brent — priced in dollars. Inference follows the same pattern.

02

SIU

the measure

One basket converts any model’s work into one comparable unit.

01

Inference

the commodity

GPUs and models produce tokens of work.

03

Dollar

the settlement

USDC paid over x402 or MPP.

Inference settles in dollars · measured and priced through SIU

Inference is the commodity, SIU is the grade, and the dollar settles.

A touchstone is the dark stone used to test the purity of metal by the mark it leaves; an assay is the formal test.

How it works

One standard, three layers.

01

The basket

A fixed, versioned set of inference tasks with objective quality gates. Output that fails the gate prices at zero.

02

The exchange rates

Each model’s cost expressed in SIU, published as spreads to the index, the way crude grades trade at differentials to a benchmark.

03

The quote extension

A touchstone-quote object carried inside an x402 or MPP payment-required response, so an agent can compare offers in one unit before paying.

Index methodology

How one Dated SIU print is calculated

All figures illustrative
Stage 01 · The basketFixed · versioned
T10.50

Short conversational completion

Reference quality

T20.30

Long-context retrieval and summarisation

Document-scale

T30.20

Code generation verified by test-pass

Pass / fail gate

One SIU is one execution of the weighted basket at reference quality.

  1. 01

    Execute the basket

    Run each fixed task class at the stated reference quality.

  2. 02

    Measure usage

    Read input, output and reasoning usage from each real run.

  3. 03

    Apply posted prices

    Calculate the observed cost from the provider’s applicable prices.

  4. 04

    Enforce quality

    Failed work prices at zero; retries carry their measured attempt cost.

  5. 05

    Cost each basket

    Weight completed task-class costs under the current basket version.

  6. 06

    Issue the print

    Weight qualifying observations, sign the result and publish the record.

Dated SIU · signed · hash-anchored print

ISSUED

The quote travels with the payment request.

The example is illustrative. Fields and version identifiers explain the transport pattern, not a production schema commitment.

Annotated HTTP 402 · illustrative
HTTP/1.1 402 Payment Required
Content-Type: application/json

{
  "accepts": [{
    "scheme": "exact",
    "asset": "USDC",
    "amount": "0.0217"
  }],
  "touchstone-quote": {
    "siu": "1.62",
    "index": "Dated SIU",
    "print": "latest",
    "methodology": "SIU-v1"
  }
}

Method

Verified, not surveyed.

Price reporting agencies survey the market; Touchstone Assay transacts in it.

Every print is measured by actually buying inference, reconciled against provider invoices, signed, and hash-anchored on chain so anyone can verify a published number was issued under a stated methodology version.

01

Executed runs

Primary evidence. Inference is purchased and measured against the current basket.

02

Routed-market flows

Observed clearing behavior supplements direct executions.

03

Published list prices

Context only. Never determinative of the print.

Publication cadence

Prints are published weekly on a stated schedule, marked provisional until reconciled against provider invoices, and corrections are published as numbered revisions alongside originals which are never edited or deleted.

For builders

A measurement interface for agents.

The MCP server exposes four narrow tools for reading, converting and verifying quotes.

get_quote

Retrieve a comparable SIU quote for an inference offer.

MCP TOOL
convert

Convert model-native units and prices into SIU.

MCP TOOL
verify_receipt

Check a receipt against the signed print and methodology version.

MCP TOOL
get_index

Read the current index and publication metadata.

FREE

The methodology is published, versioned and tied to every print.

Published prints and methodologyMethodology document →

Sequence

The publication comes first.

A sequence of intended work, not a schedule or promise.

  1. First

    The index and settlement rail

    Establish the measurement standard, publication record and payment-path quote extension.

  2. Then

    Transferable claims and a settlement token

    Extend settlement mechanics only after the reference publication is established.

  3. Thereafter

    Reference-rate licensing and derivatives support

    Support institutional use of the reference rate as the methodology matures.

Roadmap