The Central Bank of Mexico opened a prior public consultation to gather input on how card payment clearinghouses should exchange financial transaction messages with each other, as preparation for issuing Annex 5 to its draft rules on the organization, functioning and operation of card payment clearinghouses. Annex 5 is intended to set common information fields that clearinghouses must use when exchanging transaction messages, using ISO 8583:2023 as a reference, to support interoperability, security and efficiency in processing across different clearinghouses. The exercise is designed to feed into the Annex that will be incorporated into the broader draft rules that were already under public consultation from 30 December 2025 to 4 February 2026. Submissions for the prior consultation are accepted only through the Central Bank of Mexico’s online portal until 27 February 2026 at 18:00 Mexico City time (GMT-6).