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v2.0Current version

Published25/08/2026Effective date31/03/2027Release date25/08/2026

Market Facilitator Glossary

Document Summary

What? This rule sets out the common glossary of terms across Market Facilitator documentationHow? It sets out several global definitions to be used across all documentation. Over time we aim to grow this, and reduce the number of local definitionsWho? This rule impact all readers of Market Facilitator documentationWhen? This rule come into force on Day 1 of the Market FacilitatorWhy? This rule aims to align and clarify terminology

Propose change

Market Facilitator Glossary - Flexibility Market Rules - Elexon

means the Gas and Electricity Markets Authority established by section 1(1) of the Utilities Act 2000;

means the Governance Document of that name, established and maintained by the Market Facilitator;

means the execution and award by the Company of a contract for the provision of Flexibility Services by the Provider;

means a strategic planning document developed by the Market Facilitator, which sets out its key priorities, activities, timelines and deliverables for the applicable Delivery Period, for the purpose of achieving the performance objectives set by the Authority in the Governance Framework Document;

means any opportunity, idea, or proposal identified by the Market Facilitator, or notified to it by the Authority or stakeholders, which the Market Facilitator shall consider in determining whether that opportunity could assist the Market Facilitator in achieving the performance objectives set by the Authority, and whether it should be included in the Delivery Plan or Delivery Schedule.

means a detailed and granular planning document developed by the Market Facilitator, which sets out the activities, timelines and deliverables for a twelve-month period within the relevant Delivery Plan;

means a conditional exemption, granted by the Market Facilitator in accordance with paragraph 8.3 of FGD-CMP Change Management Procedure, from compliance with a specific paragraph, section, or the entirety of a Flexibility Market Rule, to the extent and for the duration specified in the derogation approval;

means a written request submitted to the Market Facilitator in accordance with paragraph 8.3.3 of FGM-CMP Change Management Procedure;

means the register maintained and published by the Market Facilitator in accordance with paragraph 7.3.10 of the Change Management Procedure, recording all active, expired, and revoked derogations, including their scope, duration, conditions, and any associated reporting obligations;

means a licence issued under section 6(1)(c) of the Electricity Act 1989 with the exception of licence issued to Independent Distribution Network Operators;

means a party which holds a Distribution Licence in respect of distribution activities in Great Britain, acting in that capacity;

means The GB Electricity Balancing Guideline, retaining and assimilating the EU law version of Commission Regulation (EU) 2017/2195;

means the websites established and maintained by Elexon in whole or in part for the purposes of delivering the Market Facilitator Arrangements;

means modifying generation and/or consumption patterns in reaction to an external signal (such as a change in price) to provide a service within the energy system;

means markets for services that provide Flexibility to the electricity system;

means common digital infrastructure enabling the collection, storage and access of asset registration data for local and national flexibility markets, covering technical asset data and flexibility service data;

means the catalogue of relevant parameters submitted by System Operators in accordance with the Flexibility Market Rules and maintained by the Market Facilitator under FGD-IMP Implementation Monitoring Procedure;

means the set of rules of that name (inclusive of rules in respect of Flexibility Market Asset Registration) owned and amended by the Market Facilitator from time to time and developed in collaboration with the other licensees, through the FGD-CPC Change Management Procedure;

means the overarching structured approach established by the Market Facilitator for the definition, documentation, publication, and coordination of Flexibility Market Rules, set out in the document of that name with the document identifier FGD-FMF;

means services provided by market participants that can adjust electricity consumption or generation in response to signals;

means any person providing Flexibility Services;

means a definition set out in the Market Facilitator Glossary;

means the suite of governance documents established and maintained by the Market Facilitator which set out the processes and procedures it shall follow in discharging its responsibilities in accordance with the Governance Framework Document;

means the document of that title issued by the Authority to establish the Market Facilitator Arrangements, as amended from time to time;

means the date specified by the Market Facilitator (following consultation in accordance with FGD-IMP Change Management Procedure, and subject to any direction of the Authority in relation to an appeal) on which an Approved Solution or an Alternative Solution, subject to any Derogation issued, shall take operational effect, and by which any affected System Operators and other relevant parties shall be required to have implemented any necessary system or process changes to comply with the Market Facilitator Rules as created or amended;

means the structured processes and responsibilities undertaken by the Market Facilitator to verify whether System Operators have implemented and are complying with the Flexibility Market Rules; and to collect information relevant to each Flexibility Market Rule to populate the Flexibility Market Catalogue and assess the effectiveness of each Flexibility Market Rule;

means the Governance Document of that name, established and maintained by the Market Facilitator;

The tracker published by the Market Facilitator detailing the implementation status of each Flexibility Market Rule (and associated change). This will be populated with Implementation Monitoring data and/or Market Facilitator Intelligence.

means a company that are licensed to maintain and manage the electricity distribution networks in Great Britain;

means the formalised rules approved by the Authority from time to time that support the electricity industry to supply energy to homes and businesses. Reference to "Industry Code" shall include all codes subject to this definition;

means a time-limited and scope-limited trial of a Sub-Market established for the purpose of research, development, or testing, in order to assess the feasibility, effectiveness, or impacts of innovative arrangements, processes, services, commercial models, or technologies within the Flexibility Markets;

means any individual or organisation that can demonstrate a legitimate interest in the Market Facilitator Arrangements, including their design, delivery, governance, operation, or impacts.

means a definition set out in a Flexibility Market Rule or Market Facilitator Governance Document;

means the Market Facilitator role performed in accordance with the Authority’s decision letter dated 29 July 2024 and pursuant to the Governance Framework Document;

means the mechanisms, roles, rules and responsibilities set out in the Governance Framework Document;

means the budget for each Business Year setting out the Market Facilitator's good faith estimate of the costs that are anticipated to be incurred in delivering the activities set out in the Market Facilitator Delivery Schedule for that Business Year and any other costs required to deliver the Market Facilitator Arrangements and associated activities;

means the Flexibility Market Rule of this name and with the document identifier FMR-GLO, which sets out the defined terms across the Flexibility Market Rules and Market Facilitator Governance Documents;

means the Market Facilitator Governance Documents and the Flexibility Market Rules;

means the quantitative and qualitative data, feedback, and insights collected, analysed, or obtained by the Market Facilitator from System Operators and other stakeholders, publicly available sources, or research undertaken or commissioned by the Market Facilitator, to support functions of the Market Facilitator;

means National Energy System Operator Limited (company number: 11014226) (and any successor to its role) established under the Energy Act 2023;

means the product of that name as defined in the Product Definitions Flexibility Market Rule;

means the date specified by the Market Facilitator on which an approved Proposed Solution or Alternative Solution to the Market Facilitator Rules shall be published and take legal effect;

means the independent leader of the SAB, responsible for setting agendas, ensuring impartiality, and guiding SAB activities;

means the product of that name as defined in the Product Definitions Flexibility Market Rule;

means the body established under the Market Facilitator Arrangements to advise, inform, and support the activities and decisions of the Market Facilitator;

means the Market Facilitator’s role in providing ongoing thought leadership, strategic advice, and industry engagement to support the effective development and operation of Flexibility Markets. It includes horizon-scanning and analysis of emerging trends; advising the Authority, DESNZ, and industry stakeholders; developing and maintaining the Delivery Plan and Delivery Schedule; and identifying, assessing, and escalating barriers to flexibility in accordance with the Governance Framework Document;

means a specific segment of the overall Flexibility Market, distinguished by a specific System Operator, procuring a specific product within a specific time period.
A Sub-market may be built of multiple distinct geographic zones, operating in different directions, clearing different volumes at different prices;

means entities that are responsible for the operation and coordination of electricity systems and markets. Specifically, this includes:
National Energy System Operator (NESO) & Distribution Network Operators (DNOs);

means the person appointed by the Market Facilitator to provide administrative and procedural support to a Workgroup or the SAB, including (without limitation) arranging meetings, preparing and circulating papers, recording minutes, maintaining records, and assisting in the coordination of activities as required by the relevant Workgroup Chair or the SAB Chair, as applicable;

means the product of that name as defined in the Product Definitions Flexibility Market Rule;

means a day (other than a Saturday or a Sunday) on which banks are open in London for general interbank business in Sterling;

0Preamble

0.0

Sections 1, 2 & 3 form the legally binding Flexibility Market Rule.

Defined terms capitalised in this document shall have the meaning given in Section 3.

GuidanceSummary of Flexibility Market Rule: Glossary

This section is provided as guidance to the Flexibility Market Rule. Therefore, it is not legally binding and falls outside of the formal change management process.

Context

This rule compiles the defined terms across the Flexibility Market Rules, and the Market Facilitator Governance Documents.

It allows for common definitions to be used across the documentation suite in an aligned way, with a central method for maintenance. It also ensures that changes to those definitions are controlled as they have direct impacts on System Operator compliance requirements.

Requirements

There are no core requirements arising from this rule directly.

The impact of the rule is via the other rules.

Implementation monitoring requirements

There are no Implementation monitoring requirements associated with this rule.

1Applicability of this Flexibility Market Rule

1.0

The definitions in this Flexibility Market Rules shall apply to the other Flexibility Market Rules as relevant from the Implementation date.

There are no direct implementation requirements from this Flexibility Market Rule.

Variations to this rule are only permitted with an approved Derogation from the Market Facilitator.

The core applicability parameters are laid out below.

Table 1: Flexibility Market Rule dates

Published Date	25/08/2026
Implementation Date	31/03/2027
End Date	-

2Glossary of Terms

2.0

Glossary of Terms

Term	Aliases	Definition
Authority	-	means the Gas and Electricity Markets Authority established by section 1(1) of the Utilities Act 2000;
Change Management Procedure	-	means the Governance Document of that name, established and maintained by the Market Facilitator;
Contract Award	-	means the execution and award by the Company of a contract for the provision of Flexibility Services by the Provider;
Delivery Plan	-	means a strategic planning document developed by the Market Facilitator, which sets out its key priorities, activities, timelines and deliverables for the applicable Delivery Period, for the purpose of achieving the performance objectives set by the Authority in the Governance Framework Document;
Delivery Plan Opportunity	-	means any opportunity, idea, or proposal identified by the Market Facilitator, or notified to it by the Authority or stakeholders, which the Market Facilitator shall consider in determining whether that opportunity could assist the Market Facilitator in achieving the performance objectives set by the Authority, and whether it should be included in the Delivery Plan or Delivery Schedule.
Delivery Schedule	-	means a detailed and granular planning document developed by the Market Facilitator, which sets out the activities, timelines and deliverables for a twelve-month period within the relevant Delivery Plan;
Derogation	-	means a conditional exemption, granted by the Market Facilitator in accordance with paragraph 8.3 of FGD-CMP Change Management Procedure, from compliance with a specific paragraph, section, or the entirety of a Flexibility Market Rule, to the extent and for the duration specified in the derogation approval;
Derogation Application	-	means a written request submitted to the Market Facilitator in accordance with paragraph 8.3.3 of FGM-CMP Change Management Procedure;
Derogation Register	-	means the register maintained and published by the Market Facilitator in accordance with paragraph 7.3.10 of the Change Management Procedure, recording all active, expired, and revoked derogations, including their scope, duration, conditions, and any associated reporting obligations;
Distribution Licence	-	means a licence issued under section 6(1)(c) of the Electricity Act 1989 with the exception of licence issued to Independent Distribution Network Operators;
Distribution Network Operator	DNO	means a party which holds a Distribution Licence in respect of distribution activities in Great Britain, acting in that capacity;
Electricity Balancing Guideline	EBGL	means The GB Electricity Balancing Guideline, retaining and assimilating the EU law version of Commission Regulation (EU) 2017/2195;
Elexon Website	-	means the websites established and maintained by Elexon in whole or in part for the purposes of delivering the Market Facilitator Arrangements;
Flexibility	-	means modifying generation and/or consumption patterns in reaction to an external signal (such as a change in price) to provide a service within the energy system;
Flexibility Market	-	means markets for services that provide Flexibility to the electricity system;
Flexibility Market Asset Registration	-	means common digital infrastructure enabling the collection, storage and access of asset registration data for local and national flexibility markets, covering technical asset data and flexibility service data;
Flexibility Market Catalogue	-	means the catalogue of relevant parameters submitted by System Operators in accordance with the Flexibility Market Rules and maintained by the Market Facilitator under FGD-IMP Implementation Monitoring Procedure;
Flexibility Market Rule	-	means the set of rules of that name (inclusive of rules in respect of Flexibility Market Asset Registration) owned and amended by the Market Facilitator from time to time and developed in collaboration with the other licensees, through the FGD-CPC Change Management Procedure;
Flexibility Market Rules Framework	-	means the overarching structured approach established by the Market Facilitator for the definition, documentation, publication, and coordination of Flexibility Market Rules, set out in the document of that name with the document identifier FGD-FMF;
Flexibility Service	-	means services provided by market participants that can adjust electricity consumption or generation in response to signals;
Flexibility Service Provider	FSP	means any person providing Flexibility Services;
Global Definition	-	means a definition set out in the Market Facilitator Glossary;
Governance Documents	-	means the suite of governance documents established and maintained by the Market Facilitator which set out the processes and procedures it shall follow in discharging its responsibilities in accordance with the Governance Framework Document;
Governance Framework Document	-	means the document of that title issued by the Authority to establish the Market Facilitator Arrangements, as amended from time to time;
Implementation Date	-	means the date specified by the Market Facilitator (following consultation in accordance with FGD-IMP Change Management Procedure, and subject to any direction of the Authority in relation to an appeal) on which an Approved Solution or an Alternative Solution, subject to any Derogation issued, shall take operational effect, and by which any affected System Operators and other relevant parties shall be required to have implemented any necessary system or process changes to comply with the Market Facilitator Rules as created or amended;
Implementation Monitoring	-	means the structured processes and responsibilities undertaken by the Market Facilitator to verify whether System Operators have implemented and are complying with the Flexibility Market Rules; and to collect information relevant to each Flexibility Market Rule to populate the Flexibility Market Catalogue and assess the effectiveness of each Flexibility Market Rule;
Implementation Monitoring Procedure	-	means the Governance Document of that name, established and maintained by the Market Facilitator;
Implementation Tracker	-	The tracker published by the Market Facilitator detailing the implementation status of each Flexibility Market Rule (and associated change). This will be populated with Implementation Monitoring data and/or Market Facilitator Intelligence.
Independent Distribution Network Operator	IDNO	means a company that are licensed to maintain and manage the electricity distribution networks in Great Britain;
Industry Code	-	means the formalised rules approved by the Authority from time to time that support the electricity industry to supply energy to homes and businesses. Reference to "Industry Code" shall include all codes subject to this definition;
Innovation Trial	-	means a time-limited and scope-limited trial of a Sub-Market established for the purpose of research, development, or testing, in order to assess the feasibility, effectiveness, or impacts of innovative arrangements, processes, services, commercial models, or technologies within the Flexibility Markets;
Interested Person	-	means any individual or organisation that can demonstrate a legitimate interest in the Market Facilitator Arrangements, including their design, delivery, governance, operation, or impacts.
Local Definition	-	means a definition set out in a Flexibility Market Rule or Market Facilitator Governance Document;
Market Facilitator	-	means the Market Facilitator role performed in accordance with the Authority’s decision letter dated 29 July 2024 and pursuant to the Governance Framework Document;
Market Facilitator Arrangements	-	means the mechanisms, roles, rules and responsibilities set out in the Governance Framework Document;
Market Facilitator Budget	-	means the budget for each Business Year setting out the Market Facilitator's good faith estimate of the costs that are anticipated to be incurred in delivering the activities set out in the Market Facilitator Delivery Schedule for that Business Year and any other costs required to deliver the Market Facilitator Arrangements and associated activities;
Market Facilitator Glossary	-	means the Flexibility Market Rule of this name and with the document identifier FMR-GLO, which sets out the defined terms across the Flexibility Market Rules and Market Facilitator Governance Documents;
Market Facilitator Rules	-	means the Market Facilitator Governance Documents and the Flexibility Market Rules;
Market Information	-	means the quantitative and qualitative data, feedback, and insights collected, analysed, or obtained by the Market Facilitator from System Operators and other stakeholders, publicly available sources, or research undertaken or commissioned by the Market Facilitator, to support functions of the Market Facilitator;
National Energy System Operator	NESO	means National Energy System Operator Limited (company number: 11014226) (and any successor to its role) established under the Energy Act 2023;
Operational Utilisation	-	means the product of that name as defined in the Product Definitions Flexibility Market Rule;
Peak Reduction	-	means the product of that name as defined in the Product Definitions Flexibility Market Rule;
Publish Date	-	means the date specified by the Market Facilitator on which an approved Proposed Solution or Alternative Solution to the Market Facilitator Rules shall be published and take legal effect;
SAB Chair	-	means the independent leader of the SAB, responsible for setting agendas, ensuring impartiality, and guiding SAB activities;
Scheduled Availability + Operational Utilisation	-	means the product of that name as defined in the Product Definitions Flexibility Market Rule;
Scheduled Utilisation	-	means the product of that name as defined in the Product Definitions Flexibility Market Rule;
Stakeholder Advisory Board	SAB	means the body established under the Market Facilitator Arrangements to advise, inform, and support the activities and decisions of the Market Facilitator;
Strategic Leadership	-	means the Market Facilitator’s role in providing ongoing thought leadership, strategic advice, and industry engagement to support the effective development and operation of Flexibility Markets. It includes horizon-scanning and analysis of emerging trends; advising the Authority, DESNZ, and industry stakeholders; developing and maintaining the Delivery Plan and Delivery Schedule; and identifying, assessing, and escalating barriers to flexibility in accordance with the Governance Framework Document;
Sub-Market	-	means a specific segment of the overall Flexibility Market, distinguished by a specific System Operator, procuring a specific product within a specific time period. A Sub-market may be built of multiple distinct geographic zones, operating in different directions, clearing different volumes at different prices;
System Operator	-	means entities that are responsible for the operation and coordination of electricity systems and markets. Specifically, this includes: National Energy System Operator (NESO) & Distribution Network Operators (DNOs);
Technical Secretary	-	means the person appointed by the Market Facilitator to provide administrative and procedural support to a Workgroup or the SAB, including (without limitation) arranging meetings, preparing and circulating papers, recording minutes, maintaining records, and assisting in the coordination of activities as required by the relevant Workgroup Chair or the SAB Chair, as applicable;
Variable Availability + Operational Utilisation	-	means the product of that name as defined in the Product Definitions Flexibility Market Rule;
Working Day	-	means a day (other than a Saturday or a Sunday) on which banks are open in London for general interbank business in Sterling;

3Implementation Monitoring Data

3.0

There is no Implementation Monitoring Data associated with this Flexibility Market Rule

FMR: Glossary - Amendment record

Guidance

This section is provided as guidance to the Flexibility Market Rule. Therefore, it is not legally binding and falls outside of the formal change management process.

Version	Published Date	Document Status	Description of Changes	Change Proposal Reference	Market Facilitator Decision Report Ref
1.0	12/12/2025	Final	Document Published	-	-
2.0	25/08/2026	Final	Document updated	CP005	CP005

3.0.2

Annex 1: Associated meta-data

Guidance

This annex is provided as guidance to the Flexibility Market Rule. Therefore, it is not legally binding and falls outside of the formal change management process.

Identifier	FMR-GLO
Title	Market Facilitator Glossary
Type	Flexibility Market Rule
Collection	Sub-Market Alignment
Audience	NESO, DNOs, Flexibility Service Providers
Expertise	Legal, Regulatory
Owner	Market Facilitator
Expected benefit	To deliver common terminology across the Flexibility Market Rules and the Governance Documents
Related end-to-end process reference	N/A
References
IsReferencedBy	All FMRs, All Governance documents
Published version number	2.0
Applicability	All Flexibility Market Rules and Market Facilitator Governance Documents
Published Date	25/08/2026
Implementation Date	31/03/2027
End Date	-
Terms of variations	Approved Derogation
IsReplacedBy	N/A
Replaces	N/A
Status	Final
Change since last version	Housekeeping change to add Implementation Tracker to the glossary
Description	What? This rule sets out the common glossary of terms across Market Facilitator documentation How? It sets out several global definitions to be used across all documentation. Over time we aim to grow this, and reduce the number of local definitions Who? This rule impact all readers of Market Facilitator documentation When? This rule come into force on Day 1 of the Market Facilitator Why? This rule aims to align and clarify terminology