# Concordium · Integra

> On Concordium, the transfer’s memo holds the ATR hash.

URL: https://integraledger.com/rails/concordium

Payment rail

## Concordium

On Concordium, the transfer’s memo holds the ATR hash. [Source: lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)

**Sources (1)**

[lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)

### Where the ATR hash rides

On this rail, the ATR hash rides in the transfer’s memo.

#### The standard

- The one transfer’s memo: H’s LCP string as a CBOR text string, which a PLT transfer wraps in CBOR tag 24. [Source: lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)

  `x402/exact/ccd`

Entry points: `@integraledger/lcp/ccd`

#### The data

Read from the published packages when the site was built; nothing here is typed by hand.

The ATR hash of the site’s example ATR, as this rail carries it

H’s LCP string, as a CBOR text string in the memo

lcp:sha256:0x8448dc1b716a5103287cb8f35e36b614ffd91e630ab8b7911833c54748ad5ca6

Computed from the site’s example ATR by this rail’s own helper in the package, when the site was built.

### What a payment on this rail proves

Of these 1 pairings, 1 have the buyer’s signature cover the ATR hash, 1 leave a public proof of it, and 1 let anyone read it back from the chain alone. [Source: lcp docs: pairings reference⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/reference/pairings.md)

Switch to Technical to see each pairing, and the sentence its record states about what a payment through it proves.

#### The standard

- **`x402/exact/ccd` Native Field Buyer signs H: yes H on chain: yes Public proof: yes Recoverable from chain: yes**

  Pattern: [Native Field (LCP §8.3.1)⁠ (opens in a new tab)](https://github.com/legal-context-protocol/legal-context-protocol/blob/c8df26d/spec/legal-context-protocol-v1.md#831-native-field)

  Where the ATR hash rides: The one transfer’s memo: H’s LCP string as a CBOR text string, which a PLT transfer wraps in CBOR tag 24.

  What a payment through it proves: The payer signed a Concordium transaction whose one transfer carries this ATR's hash, in LCP string form, as its memo. The chain accepted the transaction only with the sender's valid signature, and the memo is on chain in the finalized transfer event. This does not show that amount, payee, token or timing match the ATR's content.

  LCP profile: [x402/exact/ccd⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/lcp/profiles/x402-exact-ccd.md)

### Reading the settlement

The package reads a payment’s settlement through a reader you supply: the endpoint, the credentials, the timeouts and the retries are yours. A reader that fails never makes a payment read as failed. [Source: lcp docs: reading settlement⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md#reading-settlement)

**Sources (1)**

[lcp docs: reading settlement⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md#reading-settlement)

#### The standard

**Reader**

`CcdReader`

**Its calls**

gRPC `GetBlockItemStatus`

**A settled read carries**

`finalized` [Source: lcp docs: reading settlement⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md#reading-settlement)

### The protocols that pay on it

- [x402](https://integraledger.com/protocols/x402)

[lcp docs: rails⁠ (opens in a new tab)](https://github.com/IntegraLedger/integra-protocol/blob/66274bf/docs/guides/rails.md)