# PmtId Set of elements used to Reference a payment instruction. * Is optional * Type: `object` With the following properties: | Property | Type | Required | Description | | --- | --- | --- | --- | | `ClrSysRef` | String | Optional | Unique reference, as assigned by a clearing system, to unambiguously identify the instruction. Maximum length: 35 characters. | | `InstrId` | String | Optional | Unique identification, as assigned by an instructing party for an instructed party, to unambiguously identify the instruction. Maximum length: 35 characters. | | `TxId` | String | Optional | Unique identification, as assigned by the first instructing agent, to unambiguously identify the transaction that is passed on, unchanged, throughout the entire interbank chain. Maximum length: 35 characters | | `Uetr` | String | Optional | Unique End-to-end Transaction Reference, generated by the Payer and passed through, without modification by the payment participants through to the beneficiary. Maximum length: 36 charactersPattern: `^[a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89ab][a-f0-9]{3}-[a-f0-9]{12}$` | ## JSON schema extract ```json "PmtId": { "type": "object", "description": "Set of elements used to Reference a payment instruction.", "properties": { "InstrId": { "description": "Unique identification, as assigned by an instructing party for an instructed party, to unambiguously identify the instruction.", "type": "string", "maxLength": 35 }, "TxId": { "type": "string", "description": "Unique identification, as assigned by the first instructing agent, to unambiguously identify the transaction that is passed on, unchanged, throughout the entire interbank chain.", "maxLength": 35 }, "ClrSysRef": { "type": "string", "description": "Unique reference, as assigned by a clearing system, to unambiguously identify the instruction.", "maxLength": 35 }, "Uetr": { "type": "string", "pattern": "^[a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89ab][a-f0-9]{3}-[a-f0-9]{12}$", "description": "Unique End-to-end Transaction Reference, generated by the Payer and passed through, without modification by the payment participants through to the beneficiary.", "maxLength": 36 } } } ```