A universally unique identifier (UUID) is a 128-bit label used for information in computer systems.
Ex: 123e4567-e89b-12d3-a456-426614174000
In eCTD EU dossiers, the UUID is linking the sequence to the eCTD application to which it belongs. The UUID is used by the authorities to facilitate archiving the sequence with the correct eCTD lifecycle and some authorities also use it for automated sorting of incoming eCTD submissions to the correct eCTD lifecycle. “