Reference Model

1. Purpose of the Reference Model

This section defines the canonical element types that constitute the Canonical ESG Reference Model (CERM).

The reference model specifies:

  • The recognised structural element types
  • Their semantic role and constraints
  • The permitted relationships between them

It does not prescribe:

  • Calculation formulas
  • Reporting thresholds
  • Materiality determinations
  • Compliance interpretations
  • Regulatory acceptance

The reference model is designed to be stable, extensible, and implementation-agnostic.

Its purpose is structural coherence, not regulatory authority.

2. Core Element Types

CERM defines the following canonical element types:

  • Entity
  • Activity
  • Metric
  • Metric Identifier
  • Boundary
  • Geospatial Boundary
  • Time Period
  • Target
  • Trajectory
  • Methodology
  • Evidence
  • Assurance
  • Assertion

Each element type has a single responsibility.

Each element is referenced through stable identifiers.

Each element may be versioned when its definition changes.

3. Entity

3.1 Definition

An Entity represents an organisational unit about which sustainability assertions are made.

Examples include:

  • A legal entity
  • A reporting group
  • A business unit
  • A facility or asset

3.2 Characteristics

An Entity:

  • Has a stable identifier
  • May participate in one or more boundaries
  • May reference geospatial boundaries
  • May perform activities
  • Is defined independently of accounting or regulatory consolidation rules

Entities represent organisational structure.

They do not encode reporting scope decisions.

4. Activity

4.1 Definition

An Activity represents a real-world process, operation, or behaviour that may give rise to sustainability-related outcomes.

Examples include:

  • Fuel combustion
  • Electricity consumption
  • Material production
  • Transportation
  • Procurement

4.2 Characteristics

An Activity:

  • Occurs within a defined time period
  • Is associated with one or more entities
  • May generate one or more metrics
  • May reference a methodology
  • May reference geospatial boundaries

Activities describe operational behaviour.

They do not describe disclosure format.

5. Metric

5.1 Definition

A Metric represents a quantitative measurement or calculated value associated with sustainability performance.

Examples include:

  • Greenhouse gas emissions
  • Energy consumption
  • Emissions intensity
  • Water withdrawal

5.2 Characteristics

A Metric:

  • Has a defined unit of measure
  • Applies to a specific time period
  • Is associated with a boundary
  • May be measured or derived
  • May reference a methodology
  • May reference one or more Metric Identifiers

Metrics represent structured quantitative assertions.

They are not disclosures and do not imply compliance.

6. Metric Identifier

6.1 Definition

A Metric Identifier represents a structured or machine-readable tag associated with a metric for interoperability or digital reporting purposes.

Examples include:

  • XBRL concept identifiers
  • Regulatory taxonomy tags
  • Internal canonical identifiers

6.2 Characteristics

A Metric Identifier:

  • References a specific metric
  • May reference an external taxonomy
  • Does not modify the semantic meaning of the metric
  • Exists solely to enable digital interoperability

Identifiers support structured exchange without embedding framework semantics into CERM.

7. Boundary

7.1 Definition

A Boundary defines the organisational, operational, or value-chain scope within which activities and metrics are included.

Examples include:

  • Operational control
  • Financial control
  • Equity share
  • Upstream value chain
  • Downstream value chain

7.2 Characteristics

A Boundary:

  • Is explicitly defined and uniquely identifiable
  • May apply to entities, activities, or metrics
  • May change over time and therefore be versioned
  • Does not imply regulatory acceptability

Boundaries make scope assumptions explicit and reviewable.

8. Geospatial Boundary

8.1 Definition

A Geospatial Boundary represents the physical or geographic scope associated with an entity, activity, or metric.

Examples include:

  • Facility coordinates
  • Country or regional classification
  • Protected area designation

8.2 Characteristics

A Geospatial Boundary:

  • Supplements organisational or operational boundaries
  • May reference recognised spatial identifiers
  • Does not encode regulatory classification
  • Enables location-based modelling

Geospatial boundaries clarify spatial assumptions.

9. Time Period

9.1 Definition

A Time Period represents the temporal interval to which an assertion applies.

Examples include:

  • A fiscal year
  • A calendar year
  • A reporting quarter
  • A baseline year

9.2 Characteristics

A Time Period:

  • Has defined start and end points
  • May support historical or forward-looking assertions
  • May function as baseline or target reference

Explicit temporal definition prevents ambiguity.

10. Target

10.1 Definition

A Target represents an intended future outcome associated with sustainability performance.

Examples include:

  • Emissions reduction targets
  • Energy efficiency targets
  • Renewable energy adoption targets

10.2 Characteristics

A Target:

  • References one or more metrics
  • Specifies a baseline time period
  • Specifies one or more future time periods
  • Does not assert achievement

Targets represent declared intent.

They do not represent realised performance.

11. Trajectory

11.1 Definition

A Trajectory represents a planned or modelled pathway between a baseline and a target.

Examples include:

  • Linear reduction pathways
  • Scenario-aligned pathways
  • Internally defined planning pathways

11.2 Characteristics

A Trajectory:

  • Is associated with a target
  • May reference external scenarios or methodologies
  • Is descriptive rather than normative

Trajectories enable structured progress modelling without prescribing ambition.

12. Methodology

12.1 Definition

A Methodology describes the approach used to measure, calculate, or estimate a metric or trajectory.

Examples include:

  • Calculation standards
  • Estimation techniques
  • Allocation rules

12.2 Characteristics

A Methodology:

  • Is referenced, not embedded
  • May evolve independently of metrics
  • May reference external sources
  • Does not determine regulatory sufficiency

Methodologies provide transparency while preserving implementation flexibility.

13. Evidence

13.1 Definition

Evidence represents supporting artefacts used to substantiate assertions.

Examples include:

  • Invoices
  • Meter readings
  • Contracts
  • System logs
  • Policy documents

13.2 Characteristics

Evidence:

  • Is linked to assertions or metrics
  • Is not stored within CERM
  • Supports verification and assurance processes

CERM defines evidence relationships, not storage mechanisms.

14. Assurance

14.1 Definition

An Assurance element represents an independent evaluation of one or more assertions.

Examples include:

  • Limited assurance
  • Reasonable assurance
  • Third-party verification statements

14.2 Characteristics

An Assurance:

  • References specific assertions
  • Specifies scope and time period
  • May reference an assurance provider
  • May specify assurance level
  • Does not determine regulatory compliance

Assurance enhances transparency without embedding legal authority.

15. Assertion

15.1 Definition

An Assertion represents a declared claim about sustainability performance or state at a defined time and within a defined boundary.

Assertions may be:

  • Quantitative (e.g., a metric value)
  • Qualitative (e.g., existence of a policy)
  • Forward-looking (e.g., a target)

15.2 Characteristics

An Assertion:

  • References one or more canonical elements
  • Is bound by time period and boundary
  • May reference assurance
  • Is immutable once issued

Assertions are the atomic units of auditability within CERM.

They represent declared organisational claims, not regulatory determinations.

16. Relationships Between Elements

CERM defines explicit directional relationships, including:

  • Entities perform Activities
  • Activities generate Metrics
  • Metrics may reference Metric Identifiers
  • Metrics apply within Boundaries
  • Entities, Activities, or Metrics may reference Geospatial Boundaries
  • Metrics occur during Time Periods
  • Targets reference Metrics
  • Trajectories support Targets
  • Methodologies govern Metrics and Trajectories
  • Evidence supports Assertions
  • Assurance evaluates Assertions
  • Assertions declare values or states

All relationships are explicit and versioned.

Implicit dependencies are not permitted.

17. Versioning and Identity

Each canonical element:

  • Has a stable identifier
  • Is versioned when definitions change
  • May be superseded but not deleted

Historical versions remain referenceable to preserve audit integrity and longitudinal comparability.

18. Non-Goals of the Reference Model

The reference model does not:

  • Embed reporting framework semantics
  • Encode compliance logic
  • Perform calculations
  • Validate correctness of data
  • Interpret regulatory acceptability

These concerns are intentionally addressed in higher architectural layers.

19. Summary

The CERM reference model defines a minimal but complete set of canonical element types required to model sustainability performance in a structured, traceable, and reusable manner.

By separating:

  • Organisational structure
  • Operational activity
  • Quantitative measurement
  • Scope definition
  • Methodology
  • Intent
  • Assurance
  • Disclosure interpretation

CERM enables durable interoperability across evolving reporting ecosystems.

CERM defines structure.

It does not define compliance.

Version: v1.1.0