[F1Article 19 U.K. Settlement and return of queued payment orders
1. Payment orders that are not settled immediately in the entry disposition shall be placed in the queues in accordance with the priority to which they were designated by the relevant participant, as referred to in Article 13.
2. To optimise the settlement of queued payment orders, the ECB may use the optimisation procedures described in Appendix I.
3. Except for highly urgent payment orders, the payer may change the queue position of payment orders in a queue (i.e. reorder them) via the ICM. Payment orders may be moved either to the front or to the end of the respective queue with immediate effect at any time during daytime processing, as referred to in Appendix V.
4. At the request of a payer, the ECB may decide to change the queue position of a highly urgent payment order (except for highly urgent payment orders in the context of settlement procedures 5 and 6) provided that this change would not affect the smooth settlement by ancillary systems in TARGET2 or would not otherwise give rise to systemic risk.
5. Liquidity transfer orders initiated in the ICM shall be immediately returned as non-settled if there is insufficient liquidity. Other payment orders shall be returned as non-settled if they cannot be settled by the cut-off times for the relevant message type, as specified in Appendix V.]