Milestone 8 (M8) Code Change

The MHHS Code Workstream was responsible for ensuring that the MHHS Design was correctly translated into Code. The MHHS Code text was approved under Programme governance (M6) in August 2024 and Ofgem approved the text in November 2024 (M7), reflecting the Design up to Interim Release (IR) 8.2. 

Since M7 approval, the Design was uplifted through successive IRs, up to and including IR8.11, and this is expected to be the version that will be implemented in Code for the September 2025 M8 milestone, and which aligns to participant system builds.    

To ensure that the Code Workstream has captured all the incremental Code changes, the Code Workstream has created a Change Control Log for all changes to the approved Code since M7.

This Control Log published below, for any party to review, and it is reported monthly to the Cross-Code Advisory Group (CCAG).

M8 Control Log

The M8 Code Artefacts were presented to the Level 4 Code Drafting Working Group (CDWG) and Level 3 CCAG for endorsement, and are now progressing through the relevant Code Body governance. You can access links to the respective consultations in the Code Body Industry Consultations section below.

The M8 Code changes are expected to follow the Significant Code Review (SCR) Code change process and be approved before September 2025.  These activities are being tracked and presented to the Level 3 CCAG.  
 
The M8 Control Log was finalised in June 2025 at the point that the SCR Modifications for the Balancing & Settlement Code (BSC), Retail Energy Code (REC) and Distribution Connection and Use of System Agreement (DCUSA) were formally raised. From this point, ownership of the Cross-Code Changes has passed to Code Bodies.

Code Body Industry Consultations 

The M8 Code Artefacts are progressing through the relevant Code Body governance, and you can access links to the respective consultations below: 

P489: Update approved P478 for alignment with the latest MHHS Design 

Contact: bsc.change@elexon.co.uk  

R0241: MHHS Incremental Changes for go live

Contact: enquiries@recmanager.co.uk 

DCP456: MHHS Incremental Changes for Go Live Consultation coming soon!

Contact: dcusa@electralink.co.uk  

Cross-Code Data Specification

MHHS Energy Market Data Specification (EMDS) v1.4 contains all changes to market messages and data items across the BSC, REC and DCUSA, and is required for MHHS, reflecting the Design up to Interim Release (IR) 8.11.

Each code’s SCR Modification will approve the changes to messages and data items under their respective ownership.

You can view EMDS v1.4 in the library below.