Availability and schedules of the client simulation

The client simulation environment (IMS23) of Clearstream Europe AG (CEU) is connected to the T2S Pre-Production environment (UTEST). The comprehensive processing of test cases demands the availability of both test environments. Additionally, the test schedule that is applicable for a desired test day (that is, either T2S Synchronised Standard Day, T2S Change Request Test Day, T2S Release Day or T2S Live Timing) must be considered for a successful execution. CEU projects may offer simulations including the ClearstreamXact client simulation environment OCCT. These can even take place during a closure of the CEU client simulation environment IMS23.

The below graphic provides a forecast for the different client simulation periods until February 2027.

In both Clearstream simulation environments (IMS23 and OCCT), clients can process test cases as required between the downtimes and in parallel to project testing. For a setup preparation, clients can contact connect-test@clearstream.com.

CEU regularly offers Guided Client Simulations. This can be the case for T2S minor and major releases, if the introduction of a CEU project requires market readiness activities from market participants or if the scope of the new service necessitates dedicated test cases. 

The following client simulation is currently planned:

• Unified for New Opportunities:
  • 20 - 27 April 2026 (second testing window for Wave 2);
  • May 2026 (KUSTA Data Carrier download, testing period will be published soon).
• T2S R2026.JUN (Announcement D25047):
  • 20 April - 12 June 2026 (free testing).

The CEU client simulation environment (IMS23) and the T2S Pre-Production environment (UTEST) are regularly updated for deployment activities. Therefore, on the business day prior to the deployment activities, with the end of day procedures, CEU will close all connectivity channels towards IMS23 and UTEST.

Based on the CEU and CBL implementation schedule, IMS23 and OCCT are planned to be closed:

• From 27 March - 17 April 2026 (OCCT: to 10 April 2026);
• On 1 May 2026;
• From 18 September - 12 October 2026 (OCCT: to 2 October and on 9 October 2026); and
• From 21 December 2026 - 1 January 2027 (exact closing dates still to be confirmed).

In addition, maintenance activities are required. Therefore, on every Friday, after 12:00, testing in IMS23 and OCCT will not be possible as software updates will be installed. Additional downtimes might become necessary due to deployment activities by T2S and/or CEU.

Instructions can be entered or transmitted depending on the client’s connectivity mode. Clients acting in ICP mode provide their instructions via CASCADE Online functionality or use an automated connectivity channel (Swift, MQ, File Transfer) to IMS23. 

The current planning for the UTEST shows the following dedicated test cases that are executed under the control of T2S or ECB. The test execution impacts the processing of the "T2S Synchronised Standard Day". Test cases performed by CEU clients can therefore not be processed on UTEST as usual. As a result, the related settlement reporting cannot be transferred via T2S or CEU according to the regular test schedule.

After the implementation of the T2/T2S consolidation project in March 2023, the modified liquidity management procedures remain in UTEST. On the T2 platform, direct participants can use below the options to manage liquidity:

• Immediate Liquidity Transfer via T2 RTGS GUI
  T2 RTGS GUI can be used to transfer funds from the RTGS DCA to the T2S DCA. For details on how to use this functionality please refer to section “Liquidity Transfer – New Screen” of the Real-Time Gross Settlement User Handbook.
• Immediate Liquidity Transfer via T2 CLM GUI
  T2 CLM GUI can be used to transfer funds from the CLM MCA to the T2S DCA. For details on how to use this functionality please refer to section “Liquidity Transfer – New Screen” of the Central Liquidity Management User Handbook.
• Configure Standing Orders in CRDM
  Standing order for liquidity transfers can be created via CRDM GUI (U2A). This functionality offers the possibility to create a daily liquidity transfer. Standing orders can be configured to execute at certain time or event. Please refer to Common Reference Data Management User Handbook regarding the set-up and the related fields descriptions.
• Liquidity Transfer via A2A camt.050 message
  Participants can use the A2A channel for liquidity transfers from RTGS DCA or CLM MCA to T2S DCA. If so, the participant must provide in the creditor account of the T2S DCA to be funded. Please refer to the Real-Time Gross Settlement User Detailed Functional Specifications and Central Liquidity Management User Detailed Functional Specifications.

On Friday before the deployment of any major and minor release, the T2S Test Service Desk will refresh the UTEST by changing the recycling period in the T2S UTEST environment for matched pending instructions and for unmatched pending instructions to one business day. With this option, the pending instructions with an intended settlement day far in the past are cancelled. The change to recycling parameter will be done in the same week when the deployment is executed. The T2S Test Service Desk will revert the parameters to their original values (60 business days for pending matched instructions and five business days for pending unmatched instructions) during the deployment weekend. The changes will be valid as of the next testing day. This process will also be applied on Friday two weeks after the implementation of a major and a minor release and one week after a problem release.

Based on the test or infrastructure requirements, T2S will run the processing day using the:

• T2S Synchronised Standard Day, that is, the general daily test schedule applies.
• T2S Change Request Test Day, which is required for T2S dedicated test cases.
• T2S Release Day, which is defined for installation procedures required by the T2S Actors.
• T2S Live Timing, which is announced for specific test procedures. In UTEST the operational schedule defined for the production environment will apply:
  • 23 April 2026 (settlement against EUR)
  • 21 May 2026;
  • 31 August - 3 September 2026;
  • 7 - 10 September 2026; and
  • 15 October 2026.

During these periods, the T2S test environment UTEST will be available for a simulation until 18:00, whereas - as long as CEU does not participate in the T2S test activities - the CEU client simulation environment IMS23 will close as usual at 16:00. Periods of CEU participation in the T2S test activities with IMS23 open until 18:00 are marked in bold.

a. Times that deviate from the T2S Synchronised Standard Day are shown in bold.
Massive recycling is optional. T2S will schedule this activity only if necessary for the testing validation.