ISO 20022 element

<UETR>

Unique End-to-end Transaction Reference — a globally-unique UUIDv4 stamped on the interbank leg. What powers "where is my payment?" tracking.

Cardinality (typical)

0..1

Watch out. Never changes after it’s stamped. Lowercase UUIDv4.

Example

eb6305c9-1f7c-4a9b-9b1e-2c2f4e7a91d4