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Market Domain Data Made Easy

v 6.0

Market Domain Data

Guidance Note


A simplified guide to Elexon’s Market Domain Data

This document covers areas such as change request submissions, Meter Timeswitch Classes, Line Loss Factors and Standard Settlement Configuration. See BSCP509 Appendix 2 on the BSC Website for more about MDD.

What is Market Domain Data?

Market Domain Data (MDD) is the reference data used by Suppliers, Supplier Agents and Licensed Distribution System Operators (LDSOs) in the retail electricity market. It allows the Supplier Volume Allocation (SVA) Trading Arrangements to operate.

It includes significant information such as Standard Settlement Configuration (SSC), Profile Classes (PC), and Grid Supply Point (GSP) Groups.

MDD Users

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How is MDD managed?

MDD ensures that everyone uses the same data. It is managed on a version control basis and updated concurrently. We use version control to ensure we manage, control and audit the MDD system effectively. Elexon owns the MDD application, but CGI maintains the MDD software and database as the Supplier Volume Allocation Agent (SVAA).

How is MDD structured?

The MDD application produces structured files which are loaded into your internal systems. A new version is created when MDD information is updated and distributed (Published) to Market Participants.

The D0269 dataflow is the complete set of data (excluding Teleswitch and Primary Balancing Mechanism (BM) Unit details). These are issued in the D0280 and D0299 flows respectively.

The D0270 dataflow contains only the incremental updates of the most recent version to be published.

You are responsible for managing your own files and updating your systems. You can find further information on the structure of the MDD flows in the Data Transfer Catalogue (DTC) maintained by Retail Energy Code (REC).

How are MDD files distributed?

We publish MDD in line with the release schedule about once a month. The MDD Release Schedule, available on the BSC Website, outlines key dates, and tells you the relevant dates for each MDD version.

The SVAA distributes the MDD files to you. You can get MDD files over the Data Transfer Network (DTN) or by email. Please let the SVAA or the MDD Coordinator know which you prefer. When requesting files over the Data Transfer Network you must specify Market Participant ID and Role Code.

MDD is also available on the Elexon Portal.

The MDD Change Process

MDD is managed using version control and change procedure. This process is administered by BSCP509: Changes to Market Domain Data.

The key activities in the MDD change process are illustrated below:

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Change Request (CR) Deadline: This is the last date for when you can submit a proposed MDD change for a particular version.

More about the MDD Change Diagram

We explain the terms in the diagram on the previous page:

Elexon Assessment / SVAA Technical Assessment: We issue all changes to the SVAA (for technical assessment) following an internal review.

The SVAA sends back all changes within three working days with any issues or errors that may occur during the assessment.

Market Participant Impact Assessment: You must review all proposed changes to be incorporated in a particular version of MDD. This review enables you to raise comments on changes that may impact processes or systems. You must return comments within five working days of receiving the changes.

SVG Approval: All changes are approved by the Supplier Volume Allocation Group (SVG) before they can be committed into an MDD Publish. The SVG considers the issues raised during the market participant impact assessment, and either approves or rejects the change. Changes are presented for decision at the monthly SVG meetings.

Final Circular: The final circular is issued once the SVG has decided on the changes presented for approval. The final circular details all the changes to be included in a version of MDD.

MDD Publish: The SVAA sends the most recent MDD files to Market Participants from the Publish date.

Go-Live: All MDD changes for a particular version become effective from the go-live date.

MDD changes are split into General and Fast Track submissions. General changes relate to amending existing data items in MDD and Fast Track changes relate to submissions from new entrants and Elexon housekeeping. The Fast Track option was introduced to allow new participants get their changes into MDD in less time.

The diagram over the page demonstrates how General and Fast Track submissions are handled.

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MDD Entities

MDD consists of 64 Entities and are a breakdown of data items in MDD. BSCP509 Appendix 1 lists all MDD Entities and the authorised participant to amend the entity.

Entity Form

Entity Name

Entity Description

Entity 1

Market Participant ID

Defines an organisation that participates in the GB electricity market.

Entity 2

GSP Licensed Distribution System Operator

A party that holds the Distribution Licence regarding distribution activities within a GSP Group.

Entity 3

SVA Agent Appointment

An association between the Market Participant Identifier of an SVA Agent, and the GSP Groups in which it’s active.

Entity 4

Supplier Meter Registration Agent (SMRA) Appointment

An association of the SMR Agent and the GSP groups in which it’s active.

Entity 11

Average Fraction of Yearly Consumption Set

A set of data specifying how average consumption is split across registers for a particular GSP group, SSC and Profile Class.

Entity 12

Average Fraction of Yearly Consumption

The fraction of the annual demand that a profile allocates to the Settlement Periods covered by a Time Pattern Regime (TPR).

Entity 13

GSP Group Profile Class Average Estimated Annual Consumption (EAC)

A profile classification representing an exclusive category of customers whose consumption can be reasonably approximated to a common profile, for the purpose of attributing an EAC or Annualised Advance (AA) to individual half hours for settlement purposes.

Entity 17

Line Loss Factor Class (LLFC)

The reference for a Line Loss Factor in a distributor’s system, that applies to a group of metering systems.

Entity 18

GSP Group

A set of Distribution Systems which form a distinct electrical system and are treated as a group for the purpose of allocating errors in settlement, i.e. GSP Group Correction.

Entity 20

GSP Group Profile Class Default EAC

The default EAC is based on the mean consumption value for that Suppliers customer.

Entity 27

Clock Interval

Sets the time periods for a particular day of the week (within a calendar period) when the Time Pattern Regime is active.

Entity 29

Measurement Requirement

The set of Time Pattern Regimes for a Standard Settlement Configuration.

Entity 32

Standard Settlement Configuration

The unique Non-Half Hourly metering configuration supported by the settlement process.

Entity 33

Teleswitch Time Pattern Regime

The setup details for a Time Pattern Regime that relates specifically to a Radio Teleswitch controlled pattern of switching.

Entity 34

Teleswitch Register Rules

Allows you to maintain the list of Teleswitch Register Rules.

Entity 35

Teleswitch Contact Rule

Allows you to maintain Teleswitch Contact Rules.

Entity 36

Teleswitch Contact

Allows you to maintain the list of Teleswitch Contact Codes.

Entity 37

Teleswitch Group

Allows you to maintain the list of Teleswitch Groups.

Entity 38

Time Pattern Regime

Unique market wide reference for the pattern of switching behaviour through time, that one or more settlement registers uses. The Time Pattern Regime is used to calculate money owed for energy used by each customer.

Entity 39

Valid Measurement Requirement Profile Class

This links a measurement requirement to a valid Standard Settlement Configuration and Profile Class set.

Entity 40

Valid Settlement Configuration Profile Class

The record linking a valid Standard Settlement Configuration to a Profile Class.

Entity 45

Market Participant Role

Defines the role within the electricity market that a participant will perform. Each Market Participant must have at least one role code.

Entity 52

Meter Timeswitch Class (MTC)

A three digit code representing the type of metering system serving a customer's premise.

Entity 53

Meter Timeswitch Class for Distributor

Indicates that a particular Meter Timeswitch Class is supported by a Distributor.

Entity 54

Valid MTC SSC Combinations

A valid combination of Meter Timeswitch Class and Standard Settlement Configuration.

Entity 55

Valid MTC LLFC Combinations

A valid combination of Meter Timeswitch Class and Line Loss Factor Class.

Entity 56

Valid MTC SSC LLFC Combinations

Allows the user to link specific Line Loss Factor Classes to Valid MTC SSC combinations.

Entity 57

MTC Meter Types

Indicates the capability of the meter with the exception of Code of Practice 1-5 meters currently being used for register load billing (i.e. Profiled) which will be treated as TP (Timeswitch Programmable).

Entity 58

MTC Payment Type

Allows the user to maintain details of MTC Payment Type.

Entity 60

GSP Group Profile Tolerances

Profile Class Tolerances are used during the EAC/AA calculation and are GSP Group specific.

Entity 61

Base Primary Balancing Mechanism (BM) Unit for Supplier in GSP Group

A Primary BM unit is an association of generation units or consumption. Every Supplier ID has a Base Primary BM unit in each GSP Group; Additional Primary BM Units are extra units that a Supplier may want to register.

Entity 62

Details of Proposed Change to Unmetered Supplies Operational Information

Proposed changes to Unmetered Supplies Operational Information is incorporated in the MDD Impact Assessment Circular but is not added to any DTC flow.

Entity 63

Valid MTC SSC LLFCPC Combinations

Provides a full valid combination of Meter Timeswitch Class, Standard Settlement Configuration, Line Loss Factor Class and Profile Class.

Entity 64

SMETS Version

Describes the available versions of the Smart Metering Equipment Technical Specification (SMETS) established under the Smart Energy Code (SEC).

How do I submit a New Change Request?

To submit a new Change Request, you need to fill out a BSCP509/01 cover form with details of the change and attach the Entity forms. See BSCP509 Appendix 1 Entity Forms for a complete list of entity forms. Where you need to submit large volumes of data, you can convert the Entity forms into Excel spreadsheets for easy data entry. All headers must be accurate and in the same format as in the Word versions.

Please make sure your changes are submitted before the MDD Change Request deadline for the upcoming MDD release. We will not accept late entries.

BSCP509 Appendix 2 is useful to refer to while you are completing your submissions, as it lists the rules surrounding each entity including which fields you must fill out.

All completed changes are sent to the Market Domain Data Coordinator who will confirm receipt within two working days.

From now on, your involvement will depend on impact assessment comments. If there are any issues with a change, the MDDC will contact the originator.

After the SVG has approved or rejected changes for a version, we issue a Final Circular containing all changes which we will incorporate into that version of MDD.

The diagram below shows the expected interactions between the originator of a change and the MDDC:

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How do I set up a new Role Code?

You can register multiple role codes against your MPID. The role codes define the roles and activities the organisation undertakes within the SVA Trading Arrangements.

There are currently 34 roles codes active in MDD. A full list of role codes with their descriptions can be found in MDD, or the online tables on the Elexon Portal.

The diagram below shows how “Company A Ltd” is set up against multiple roles.

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When setting up a new role code, you must complete Entity 1 (Market Participant ID) and 45 (Market Participant Role) including details of the role code. The ‘Effective From Date {Market Participant Role}’ is the date when the Market Participant role will become effective. You must fill in Address Line 1 of the Entity 45 form with your company name, and use subsequent lines for the organisation’s address. Role code details are set out like this:

Market Participant ID


Market Participant Role


Effective From Date


Effective To Date {MPR}

Address Line 1

Justin Enterprises Ltd

Address Line 2

1 Waterway Crescent

Address Line 3

Address Line 4

Post Code


Distributor Short Code

How do I set up New Data Items?

Depending on your role, you can set up new data items in MDD. Other participants may own some data items and therefore both parties must agree these before submitting them formally.

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Meter Timeswitch Class

Meter Timeswitch Classes (MTCs) are three digit codes allowing Suppliers to identify the metering installed in Customers' premises. They indicate whether the meter is single or multi rate, pre-payment or credit, or whether it is "related" to another meter.

A related meter refers to where there are two meters in a property and is one for general load and one for heating. In this case a Supplier must register both meters.

MTC Categories


Specific to Distribution Networks


Currently not in use


Common codes for Related Metering

510 - 799

Specific to Distribution Networks for Related Metering

800 - 999

Common Codes

You can set up a new MTC by completing an Entity 52 “Meter Timeswitch Class” form.

To enable the MTC in a particular distribution area, you will need to complete an Entity 53 form.

Where a Supplier puts this request forward, the relevant Distributor must approve this before making a formal submission.

When setting up a new MTC you need to specify:

MTC Meter Type: the physical capabilities and purpose of the meter and categories such as Teleswitch, Timeswitch, Import/Export, Unmetered and Code of Practice (CoP) related Meters.

MTC Payment Type ID: method of payment used for any Metering Systems against that MTC. Categories can include methods such as token and key meters or credit and prepayment.

MTC Type Indicator: determines whether the Meter is Non Half Hourly (NHH), Half Hourly (HH) or Non-specified.

MTC Related Metering System Indicator: indicates Meters that are capable of being used in a related Meter Point Administration Number (MPAN) setup. A related MPAN setup could include a number of physical meters to deal with separate demand loads.

Line Loss Factor Class

Line Loss Factor Classes (LLFCs) relate to the Distribution Network Operator (DNO) and DNOs must maintain these values.

New Line Loss Factor Classes

You can set up a new LLFC by completing an Entity 17 Form. The Distributor submits the desired values, Effective From Date, and an appropriate description for the LLFC. Metering System Specific LLF Class indicator types are:


General LLFC for Import Active Energy


MS Specific LLFC for Import Active Energy


General LLFC for Export Active Energy


MS Specific LLFC for Export Active Energy

When submitting new LLFC values in MDD, the Distributor should send the associated Calculation Self-Assessment Document (CSAD) with the D0265 (Line Loss Factor Data File) flow. This speeds up the LLF validation process and helps us to sort out any issues before the Go-Live Date. All D0265 and supporting CSAD information should be sent to

End-Dating Line Loss Factor Classes

To end-date an LLFC, you will need to complete an Entity 17 form with an Effective To Settlement Date. The LLFC will remain valid for all Settlement Dates up to and including the Effective to Settlement Date {LLFC}. The Distributor must also send an updated D0265 flow in the event that an LLFC has been end-dated.

Amending Line Loss Factor Class Descriptions

A Distributor can amend the description of an LLFC as required by completing the Line Loss Factor Class Description field on the Entity 17 form. The description field should contain no more than 30 characters including spaces. The Effective From Date remains unchanged.

Standard Settlement Configurations

The Standard Settlement Configuration defines how a NHH Meter is configured for Settlement. It defines how many registers (TPRs) the meter has and the times at which the registers record consumption.

Setting up a new SSC

To set up an SSC, you need to ensure that the desired value is available in MDD. The MDD Coordinator can confirm this, or you can choose the next available four digit code in MDD. You can introduce a new SSC by completing an Entity 32 “Standard Settlement Configuration” form. There are two types of SSCs; Teleswitch and Timeswitch. The sections below detail how to set up the two types of SSC and which forms you need to complete. Please refer to Appendix A for the complete set of entity forms required for a new SSC.

Teleswitch SSCs

Teleswitch Meters are centrally coordinated by the Teleswitch Agent using the Central Teleswitch Control Unit (CTCU). The CTCU forwards switching patterns to the BBC transmitter who sends out instructions by radio transmission.

The setup of Teleswitch SSCs relates to the Teleswitch Switching instructions which control heating and register load. A "Simple Teleswitch" setup turns the switched load on at set times during off peak periods. A “Double Teleswitch‟ setup controls both the base and switched load.

The diagram below shows a basic overview of the Teleswitch hierarchy. The Teleswitch User ID relates to an LDSO acting in its capacity as Radio Teleswitch Access Provider. The Teleswitch Group ID is a code relating to a number of Teleswitch metering systems controlled by a Teleswitch User.

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The Teleswitch Switching times for an SSC will not be held in MDD, as the times can be physically reprogrammed on the meter using the existing Teleswitch register rules. To find out more about Teleswitch Switching times, please contact the MDDC.

Teleswitch information

Teleswitch User ID

A code representing the organisation which controls the Teleswitch group (LDSOs).

Teleswitch Group ID

This identifier is given to a group of Metering System Identifiers governed by a specific Teleswitch User ID.

Teleswitch Switch ID

A code representing one of the logical contacts supported by Teleswitch metering.

Teleswitch Register Rule

A number distinguishing between the switching relationships between Teleswitch contacts and settlement registers associated with a Time Pattern Regime.

Teleswitch Contact Code

A character identifier (A, B, C, D) identifying logical switching of the Teleswitch Register Rule.

Teleswitch Contact Rule

Indicates whether the TPR is ‘1’ on or ‘0’ off.

Timeswitch SSCs

When setting up a Timeswitch SSC, you need to complete an Entity 38, with the Teleswitch/Clock indicator field set to "C". The GMT indicator simply means whether the meter operates only on Greenwich Mean Time or whether it switches to British Summer Time.

The Entity 27 ‘Clock Interval form sets the configuration of the TPR’s switching times in a meter.


Week Day Id

Start Day

Start month

End Day

End Month

Start Time

End Time









The form is completed by ensuring that the switching times for each meter register (or TPR), for each day of the week is accounted for as seen in the example above.

How do I register Primary BM Units in MDD?

Primary BM Units are units of trade in the Balancing Mechanism for generation or consumption. All Suppliers must register a Primary BM Unit (also known as Base Primary BM Units) in every GSP Group once they become active in their Supplier role. They measure the amount of energy supplied by Suppliers and are a collection of meters aggregated into one set. All meters for a particular Supplier ID and GSP Group are amalgamated into a single Primary BM Unit.

Supplier Primary BM Units can be setup in MDD by completing a BSCP509 Entity 61 form. This details the BM Unit ID, the GSP Group and MPID that they are registered for.

Base Primary BM Units

Every Supplier ID must have an initial Base Primary BM Unit in each GSP Group for Settlement purposes.

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The naming convention surrounding Base Primary BM Units (as illustrated above) is as follows:

(2_) = Supplier Primary BM Unit

(_A) = GSP Group _A

(SUPP) = four Character Supplier ID

Additional Primary BM Units

Suppliers can also register additional Primary BM Units against their existing Supplier ID. There is no limit to the number of additional Primary BM Units a Supplier can register in each GSP group.

Additional Primary BM Units are named similarly to Base BM Unit, apart from the three digit code at the end which is incremented.

Additional Primary BM Unit “2__ASUPP001”

How do I deregister Primary BM Units from MDD?

When a Supplier ID is due to be terminated, all the Primary BM Units associated with that ID will also be discontinued (unless another Supplier is taking over the responsibility of the Primary BM Units). You can deregister these Primary BM units by completing an Entity 61 form with the desired Effective To Date specified.

Combination Data

A number of data items are combined in MDD to give a full picture of what metering configurations are valid. The data items are as follows: Meter Timeswitch Classes, Line Loss Factor Classes, Standard Settlement Configuration and Profile Classes.

You are advised to link up these data items in MDD to give other participants an accurate view of what configurations are valid.

For Non Half Hourly combinations, the relevant combination tables are Valid MTC SSC Combination, Valid MTC LLFC SSC Combination and Valid MTC SSC LLFC PC Combination. For Half Hourly it is Valid MTC LLFC Combination. LDSOs must update their combination data accordingly. Where a Supplier wants to operate a certain metering configuration in a LDSOs area, they need to get consent from the LDSO who will make the relevant submissions on their behalf.

The diagram below show how each data item interlinks to create combination data:

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MDD Files

After each MDD Publish the SVAA will distribute the latest version of MDD through the DTN or by mail.

D0269Market Domain Data Complete Set

D0270Market Domain Data Incremental Set D0280– Teleswitch Contact to Register Mapping File

D0299BM Unit Registration Data File

D0278– Teleswitch Pool Market Domain Data Interface File

D0267– Pool Settlements Timetable File

D0227Standard Settlement Configuration Timetable file

D0286– Data Aggregation and Settlements Timetable file

P0015Profile Data File

P0186– Half Hourly Default EAC

P190GSP Group Profile Class Tolerances

GSP Group Profile Class Default EAC


The diagram below show the entities needed to set up a Standard Settlement Configuration. The flows diverge after the new SSC depending on whether you’re setting up a Clock Switched Meter or a Teleswitch Meter.

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Need more information?

Market Domain Data Contact Details

Market Domain Data Coordinator:

For further information please contact the BSC Service Desk or call 0370 010 6950.

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