The txid field determines the identifier of the transaction. The purpose of this field is to serve as an element that enables the recipient's PSP to present the payment reconciliation feature to the recipient user. In the pacs.008, it is referenced as TransactionIdentification or idConciliacaoRecebedor. In terms of operational flow, the txid is read by the payer's PSP application, and after the payment is confirmed, it is sent to the SPI via pacs.008. A pacs.008 is also sent to the recipient's PSP, containing, in addition to all the usual payment information, the txid. Upon detecting a receipt with a txid, the recipient's PSP is able to communicate with the recipient user, informing them that a specific payment has been settled. The txid is created exclusively by the recipient user and is their responsibility. The txid, in the context of representing a charge, is unique per CPF/CNPJ of the recipient user. It is the responsibility of the recipient's PSP to validate this rule in the Pix API.