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DEX 27.1 Release Summary

An overview of changes included in DEX 27.1

New DEX 27.1

Thank you for visiting Safe Financials, home of the CREST Simulator.

Our cost-effective, on-demand testing facility for your CREST back office system enables you to test all the latest CREST updates well in advance of them going live, with the full support of our Help Desk. This enables firms to be well prepared and minimise the impact of system changes on their day-to-day business.

DEX 27.1: Overview of Changes

Euroclear has introduced a new DEX release: DEX 27.1, which is due to go live in November 2021. Here, we will outline the upcoming changes as well as how the CREST Simulator can help you get prepared.

Diary Changes

The Term DBV settlement window (diary event 751) will be extended to accommodate earlier settlement of TDO and TDA transactions which include a Fixed Income security. The diary event will be moved from 15.00  to 05.57.

Diary Event 261 (Start Equity DBV Settlement) will be introduced to allow DBV and TDO transactions containing equities to settle.

How CREST Simulator can help

We have full timetable testing functionality available. Diary events trigger back office processing; we can amend times to suit your needs, enabling you to complete your testing swiftly and easily.

Open-ended Term DBV in Fixed Income Securities

The release will introduce the ability to set an open-ended return date for DBVs containing Fixed Income securities. The two-year return date maximum limit will be removed, allowing any return date up to the system end date of 31/12/2999.

Currently, DBVs in Fixed Income securities with no return date set becomes an overnight DBV. The new release will prevent this from happening. Instead, any return date left blank will automatically be set to 31/12/2999.

How CREST Simulator can help

With the sizeable list of Fixed Income categories available, this is a significant change for organisations currently offering the DBV service. To facilitate testing, we have a number of securities available within each category, which can be amended to suit your needs (dependent on your User/Environment setup).

New version of CREST GUI

Version 15.02 of CREST GUI will be decommissioned and a new version introduced. This will include some changes to the Collateral Instruction Details screen to allow for the amendment of the Next Value Interest Rate and Next Value Return Date fields.

Please note that users currently using CREST GUI version 15.02 will be required to upgrade to another version so as not to lose CREST GUI.

File transfer

There are no version changes to the NDDN message. However there are changes relating to how the Return Date is populated and used. This change will determine whether your message will create an Overnight DBV (DBV) or a Term DBV (TDO) transaction going forward.

There are no version changes to the ARPA message. However there are changes relating to existing fields on the current message version and how they are used i.e. Effective Date & Return Date.

How CREST Simulator can help

All the new message functionality is available to test allowing you to assess how these new DBV changes and will impact your current and future DBV requirements.

Get ahead with the CREST Simulator

The CREST Simulator helps CREST back office users to get prepared for changes well in advance, fully supported by us. It offers:

  • On demand testing without the need to pre-book testing days.
  • Fully supported Help Desk to assist with any queries you may have.
  • Weekend/out of hours usage available on request.
  • Flexible pricing structure to suit specific needs.


To get prepared with all the support you need from us, please get in touch at support@sfl.co.uk.


Ready to sign up or want more information?

If you would like to learn more about the Simulator and how it can help your system testing, training and development, please get in touch with us via our Contacts page.

Safe Financials Ltd

1st Floor Waverley Court
Wiltell Road
WS14 9ET

+44 (0)330 390 5215

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