ISD
Industry Standing Data
Industry ReformsIndustry Standing Data is the MHHS-era reference dataset that replaces Market Domain Data (MDD), holding the valid codes and configurations systems use to validate MPANs and process settlement.
Industry Standing Data (ISD) is the reference data backbone for the MHHS world. It replaces Market Domain Data (MDD), the long-standing dataset of valid market codes and combinations that systems relied on for validation and settlement.
ISD vs MDD:
| MDD (legacy) | ISD (MHHS) | |
|---|---|---|
| Role | Valid combinations, reference codes | Same role, MHHS-era model |
| Status | Frozen, retained around 5 years (to ~Sep 2030) | Live, versioned catalogues |
| Cadence | Periodic releases | More frequent releases during transition |
| Source | Elexon | Elexon ISD Data Store |
Why both exist at once: During the migration, some meters are settled the legacy way and some under MHHS. Systems therefore need legacy MDD codes and new ISD entities at the same time. MDD is frozen rather than deleted so historic reconciliation still works.
What ISD contains: Distributor configurations, valid DUoS Tariff ID and loss-factor combinations per distributor, settlement segment definitions, and participant reference data. Early ISD releases had documented quality issues, which is why clean, structured reference data is in demand across the industry.
Note on SSC and TPR: SSC-to-TPR mappings do not sit in ISD. They are maintained on the REC Portal as the enduring source for MHHS supply numbers.
Related terms
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