This field is a Brazil Central Bank (BCB) requirement to track all steps of Pix transactions. Basically, there are two steps to a Pix transaction: 1. Initialize a transaction 2. Confirm a transaction The end_to_end_id is sent to the BCB in both steps in order to identify all transaction information.

Payment order cancellation reason:

• ACCT - Paying or receiving user's transactional account closed
• BLCK - Paying or receiving user's transactional account blocked
• CCLD - Recurring payments authorization cancelled
• FAIL - Settlement process failure or error
• OTHR - Paying or receiving user requested cancellation for other reasons
• SLBD - Paying user request
• SLCR - Receiving user request

Account token - an access token encoded with a Pismo account ID. Tokens can expire quickly, which can result in a 401 Unauthorized message.

A unique ID to ensure the operation remains idempotent, allowing for operation repitition without causing unintended effects or duplication. An idempotent operation is one that can be applied multiple times, yet the outcome remains the same. it ensures that network errors, retries, or failures can occur without introducing inconsistencies.