ISO 22095-2
(Main)Chain of custody — Part 2: Requirements and guidelines for mass balance
Chain of custody — Part 2: Requirements and guidelines for mass balance
Chaîne de contrôle — Partie 2: Exigences et lignes directrices pour le bilan massique
General Information
- Status
- Not Published
- Technical Committee
- ISO/TC 308 - Chain of custody
- Drafting Committee
- ISO/TC 308 - Chain of custody
- Current Stage
- 6000 - International Standard under publication
- Start Date
- 29-Oct-2025
- Completion Date
- 10-Jan-2026
Overview
ISO 13662 - Chain of custody - Mass balance - Requirements and guidelines (FDIS 2025) provides requirements and practical guidance for applying the mass balance chain of custody model (as defined in ISO 22095) to material and product flows. The standard explains how to attribute specified characteristics (for example renewable feedstock, social or sustainability attributes) to outputs when physical segregation is not feasible, while ensuring transparent documentation, avoidance of double counting, and consistent communication and claims.
Key topics and requirements
- Scope and purpose: Applies to any material or product flow using a mass balance approach; clarifies differences from controlled blending and book and claim models.
- Definitions and terminology: Builds on ISO 22095 terminology (chain of custody, specified characteristics, attribution, administrative record, etc.).
- System boundaries: Requirements for defining geographical and temporal boundaries for mass balance accounting.
- Time periods: Guidance on appropriate reporting periods and reconciliation intervals.
- Material and credit reconciliation: Rules for tracking inputs, outputs and administrative records to support entitlement to specified characteristics.
- Conversion and consumption factors: Requirements for documenting and applying conversion/consumption factors where inputs are transformed into outputs.
- Implementation methods: Describes main methods such as the rolling average percentage method and the credit method, and when each is appropriate.
- Avoidance of double counting: Controls to prevent multiple claims on the same specified characteristics.
- Returned materials and products: Treatment of returns within the mass balance system.
- Claims and communication: Requirements for transparent market communication, labelling, and internal/external claims; includes a designation system (normative) and examples (informative).
- Annexes: Practical guidance and worked examples (set‑up, credit accounts, conversion factors, designation examples).
Applications and who uses it
ISO 13662 is intended for organizations and stakeholders implementing mass balance chain of custody systems across complex supply chains, including:
- Manufacturers, processors and converters
- Supply chain and sustainability managers
- Certification bodies and auditors
- Brokers and traders
- Policy makers and standard setters
Industries where mass balance is commonly applied include transportation, agriculture, textiles, forestry, construction, chemicals, metals and steel, energy, glass, plastics, organics and inorganics.
Related standards
- ISO 22095:2020 - Chain of custody - General terminology and models (normative reference used throughout ISO 13662).
- Prepared by ISO/TC 308 (Chain of custody).
Keywords: ISO 13662, mass balance, chain of custody, rolling average percentage method, credit method, conversion factor, system boundary, claims, ISO 22095.
ISO/FDIS 13662 - Chain of custody — Mass balance — Requirements and guidelines Released:19. 08. 2025
REDLINE ISO/FDIS 13662 - Chain of custody — Mass balance — Requirements and guidelines Released:19. 08. 2025
Frequently Asked Questions
ISO 22095-2 is a draft published by the International Organization for Standardization (ISO). Its full title is "Chain of custody — Part 2: Requirements and guidelines for mass balance". This standard covers: Chain of custody — Part 2: Requirements and guidelines for mass balance
Chain of custody — Part 2: Requirements and guidelines for mass balance
ISO 22095-2 is classified under the following ICS (International Classification for Standards) categories: 03.100.01 - Company organization and management in general. The ICS classification helps identify the subject area and facilitates finding related standards.
ISO 22095-2 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
FINAL DRAFT
International
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ISO/FDIS 13662
ISO/TC 308
Chain of custody — Mass balance —
Secretariat: NEN
Requirements and guidelines
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2025-09-02
Voting terminates on:
2025-10-28
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ISO/FDIS 13662:2025(en) © ISO 2025
FINAL DRAFT
ISO/FDIS 13662:2025(en)
International
Standard
ISO/FDIS 13662
ISO/TC 308
Chain of custody — Mass balance —
Secretariat: NEN
Requirements and guidelines
Voting begins on:
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
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ii
ISO/FDIS 13662:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Differentiation between chain of custody models . 6
4.1 General .6
4.2 Differences between the mass balance model and the controlled blending model .7
4.2.1 Credits and TIECs — Entries 1 and 5 .7
4.2.2 Geographical system boundary — Entry 2 .7
4.2.3 Item-based expectations — Entry 3 .7
4.2.4 Expectation of physical presence — (Entry 4) .7
4.2.5 Physical separation of material or products — Entries 6 and 7 .7
4.3 Differences between the mass balance model and the book and claim model .7
4.3.1 Credits and transferrable instruments with entitlement to claim (TIEC) —
Entries 1 and 5 .7
4.3.2 Geographical system boundary — Entry 2 .8
4.3.3 Administrative document flow and physical material or product flow — Entry 5 .8
5 Requirements for mass balance chain of custody model . 8
5.1 General .8
5.2 Set-up of a mass balance system .9
5.3 System boundary . .11
5.3.1 General requirements .11
5.3.2 Geographic area . 12
5.3.3 Balancing period. 12
5.4 Evaluation and claim periods . 12
5.4.1 Evaluation period . 12
5.4.2 Claim period . 13
5.5 Types of data, data sources and data quality . 13
5.6 Material and credit reconciliation . 13
5.7 Conversion and consumption factor .14
5.8 Avoidance of double counting in mass balance systems . 15
5.9 Returned materials and products . 15
6 Mass balance model implementation methods .15
6.1 Mass balance model rolling average percentage method . 15
6.2 Mass balance model credit method.16
6.2.1 General .16
6.2.2 Characteristics of mass balance model credits .17
6.2.3 Attribution principles .17
7 Claims and communication .18
7.1 General requirements .18
7.2 Business-to-business communication .19
7.3 Business-to-consumer communication . 20
Annex A (informative) Set-up of a mass balance model .21
Annex B (informative) Examples for setting up a credit account and utilization of conversion
and consumption factors for the credit method .22
Annex C (normative) Designation system for mass balance chain of custody model .27
Annex D (informative) Examples for designation system for mass balance model .35
Bibliography .44
iii
ISO/FDIS 13662:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 308, Chain of custody.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO/FDIS 13662:2025(en)
Introduction
The mass balance model is one of five chain of custody models outlined in ISO 22095. A mass balance
model offers different methods for organisations to mix or co-process inputs with and without specified
characteristics while transparently documenting the movement of the inputs and their specified
characteristics. This is to ensure that the credits or specified characteristics are appropriately accounted
for and attributed to outputs within the same system boundary.
NOTE Mixing and co-processing includes activities where those in the value chain (i.e. brokers) do not physically
mix or co-process mass balanced material or products.
A mass balance model is ideally suited for certain situations, such as when identity preserved, segregated,
or controlled blending chain of custody models are not feasible. For instance, in some supply chains,
materials or products with specified characteristics are mixed or co-processed with materials or products
without specified characteristics. New materials or products are then produced. It is not possible to
distinguish which of these new materials or products were derived from inputs with, and without, specified
characteristics. However, the quantity of input with specified characteristics, such as renewable feedstock
or fair trade labour practices, are in the system. Therefore, it becomes appropriate to pass forward those
specified characteristics through a chain of custody model. Many industries currently use a mass balance
model including transportation, agriculture, textiles, forestry, construction, chemicals, metals, steel, energy,
glass, plastics, organics and inorganics.
However, the mass balance model may be applied differently in the market based on the criteria selected.
This may create confusion and reduce its credibility among consumers, policy makers, standard setters,
and other stakeholders. This document provides guidance to explain the mass balance chain of custody
model and limit the risk of confusion on mass balance model communication (for example claims) in the
marketplace and throughout the value chain.
This document helps organizations outline technical choices, define system boundaries, and specify methods
of attribution. In addition, it provides guidance on communication and claims.
v
FINAL DRAFT International Standard ISO/FDIS 13662:2025(en)
Chain of custody — Mass balance — Requirements and
guidelines
1 Scope
This document provides requirements and guidelines for the application of the mass balance chain of custody
model, as defined in ISO 22095, to any material or product flow within mass balance systems, including how
to attribute specified characteristics to flows of such processes.
This document provides requirements and guidelines for the following matters, amongst others:
— differentiations from controlled blending and book and claim models;
— general requirements for organizations active in a mass balance chain of custody model;
— system boundaries including geography and time;
— conversion factors;
— the rolling average percentage method;
— the credit method;
— transparency, communication and claims.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 22095:2020, Chain of custody — General terminology and models
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 22095 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
administrative document
documentation that uniquely identifies the entitlement to claim the ownership of the specified characteristics
(3.28) of materials or products at the respective point in the chain of custody
3.2
administrative document flow
process that uniquely identifies the entitlement to the claim of ownership and the transfer of the claim of
ownership of the specified characteristics (3.28) of materials or products through the chain of custody
ISO/FDIS 13662:2025(en)
3.3
administrative record
documentation or guarantee that warrants unique ownership of the entitlement to claim the consumption
or use of specified characteristics (3.28) at a point in the chain of custody
Note 1 to entry: “Specified characteristics” is defined in ISO 22095:2020, 3.2.5 and “chain of custody”
is defined in ISO 22095:2020, 3.1.1.
3.4
administrative record flow
movement or transfer of unique ownership of the entitlement to claim consumption or use of specified
characteristics (3.28) within the chain of custody
3.5
associated information
information related to the material or product such as description, quality, assurance, or life cycle related data
3.6
attribution
assignment of credits (3.13) (credit method) or specified characteristics (3.28) (rolling average method) to
outputs (3.22) or part of the outputs
3.7
balancing period
time frame when the credits (3.13) associated with inputs (3.18) and outputs (3.22) with specified
characteristics (3.28) are balanced in the temporal boundaries of the system
3.8
book and claim model
chain of custody model in which the administrative record flow (3.4) is not necessarily connected
to the physical flow of material or product throughout the supply chain
Note 1 to entry: This chain of custody model is also referred to as "certificate trading” or "credit trading”.
Note 2 to entry: Within a book and claim system, a Transferable Instrument with Entitlement to Claim (TIEC) represents
the right to claim specified characteristics (3.28), which can be bought, sold, transferred between organizations (3.21),
or retained on behalf of other organizations. The term “certificates” is used in ISO 22095, whereas the term ”TIEC” is
used here for consistency. TIEC is defined in 3.31.
[SOURCE: ISO 22095:2020, 3.3.5, modified — In Note 1 to entry the wording has been modified, Note 2 to
entry has been added.]
3.9
claim
declared information regarding the specified characteristics (3.28) of a material or product
Note 1 to entry: Information can be any message or representation, including textual, pictorial, graphic or symbolic
representation in any form in the context of a commercial communication.
Note 2 to entry: A claim can be made using various means or channels for example on the product or physically
attached to the product or physical or virtual information about the product.
[SOURCE: ISO 22095:2020, 3.5.10, modified — Notes 1 and 2 to entry have been added.]
3.10
claim period
time frame when claims (3.9) can be made on materials or products
ISO/FDIS 13662:2025(en)
3.11
consumption factor
specification of conversion factor (3.12) that considers individual steps and/or individual inputs (3.18) in a
system boundary with one or more inputs and/or one or more steps, rather than aggregated over steps and/
or inputs, which results in a single overall conversion factor
Note 1 to entry: In the case of a single input and single step process, the conversion factor and consumption factor
would be equal.
3.12
conversion factor
ratio which is used to determine the quantity of output (3.22) or part of the output with specified
characteristics (3.28) that can be obtained from the quantity of the input (3.18) with specified characteristics,
taking into account any losses
3.13
credit
representation of the quantity of units (3.33) available for attribution with entitlement to claim the
ownership of specified characteristics (3.28)
3.14
credit account
system used by organizations (3.21) to record and track the credits (3.13) associated with specified
characteristics (3.28)
3.15
destructive process
processing for the purpose of the recovery of materials without preserving the original product or component
EXAMPLE Disintegration (crushing, shredding, milling, grinding), concentration (separation, non-destructive
depollution, homogenization), refining and re-melting.
[11]
[SOURCE: ISO 59014:2024 , 3.6, modified — ‘process to obtain secondary materials without any intent of’
deleted, replaced with ‘processing for the purpose of the recovery of materials without’; Example modified:
‘destructive depollution’ to ‘non-destructive depollution’.]
3.16
double counting
accounting for inputs (3.18) or outputs (3.22) or specified characteristics (3.28) more than once
[5]
[SOURCE: ISO 14050:2020 , 3.5.25]
3.17
evaluation period
time frame when the performance of the chain of custody system is monitored, measured, analysed
and evaluated by conducting audits to assess the performance of the chain of custody system procedures
and the conformance with all applicable requirements
3.18
input
material or product that enters a chain of custody system boundary (3.29)
Note 1 to entry: Input can be used at any stage of the supply chain.
Note 2 to entry: Input can also include reused and recycled materials or products.
Note 3 to entry: Input can have associated information (3.5), such as specified characteristics (3.28).
ISO/FDIS 13662:2025(en)
3.19
mass balance model
chain of custody model in which materials or products with a set of specified characteristics (3.28) are mixed
or co-processed according to defined criteria with materials or products without that set of characteristics
Note 1 to entry: The proportion of the input (3.18) with specified characteristics might only match the initial
proportions on average and will typically vary across different outputs (3.22).
Note 2 to entry: The mass balance model establishes the relation between inputs and outputs with specified
characteristics and the distribution of those inputs and outputs via attribution (3.6).
Note 3 to entry: For the mass balance model, two implementation methods are specified: rolling average percentage
method and credit method.
Note 4 to entry: In the mass balance model, the specified characteristics cannot be transferred between different
organizations (3.21) independent of physical materials or products.
[SOURCE: ISO 22095:2020, 3.3.4, modified — Note 2 to entry has been modified, Notes 3 and 4 to entry have
been added.]
3.20
non-proportional attribution
assignment of credits (3.13) to one or more outputs (3.22) irrespective of the proportion of the individual
outputs with respect to the total output
3.21
organization
entity or group of people and facilities with an arrangement of responsibilities, authorities and relationships
and identifiable objectives
Note 1 to entry: An organization can encompass multiple (production/geographical) sites.
Note 2 to entry: An organization includes a corporate group defined as a number of consolidated legal entities guided
by a parent company.
[9]
[SOURCE: ISO 26000:2010 , 2.12, modified — Note 2 to entry has been added.]
3.22
output
material or product that leaves a chain of custody system boundary (3.29)
Note 1 to entry: Output can be created at any stage of the supply chain.
Note 2 to entry: Output might include other products resulting from production processes.
Note 3 to entry: Product covers material or energy products.
3.23
primary data
quantified value of a unit (3.33) process (3.24) or an activity obtained from a direct measurement,
or a calculation based on direct measurements at the original source
[5]
[SOURCE: ISO 14050:2020 , 3.6.34]
3.24
process
set of interrelated or interacting activities that use inputs (3.18) to deliver an intended output (3.22)
Note 1 to entry: A process can include provision of services, such as storage or transportation (3.32).
Note 2 to entry: Technical operations of processes include continuous process, semi-batch, and batch.
Note 3 to entry: A process can also be a discrete process with a discrete time boundary such as production of a fashion
collection or a furniture line.
ISO/FDIS 13662:2025(en)
[1]
[SOURCE: ISO 9000:2015 , 3.4.1, modified — The word “result” has been replaced by “output”. Notes 1 to 6
to entry have been deleted. Notes 1, 2 and 3 to entry have been added.]
3.25
proportional attribution
assignment of credits (3.13) to one or more outputs (3.22) according to the proportion of the individual
outputs with respect to the total output
3.26
requirements setter
person, organization (3.21), regulator or independent third-party program operator that specifies
requirements for a particular chain of custody
Note 1 to entry: Organizations active in the chain of custody can also act as the requirements setter.
Note 2 to entry: The mass balance system is defined by the requirements setter.
[SOURCE: ISO 22095:2020, 3.4.3, modified — Notes 1and 2 to entry have been added.]
3.27
similar in nature
material, products, or concepts that share common characteristics e.g. functionalities, qualities, composition
or attributes, making them alike in fundamental aspects
3.28
specified characteristic
set of product and/or production characteristics that the chain of custody is designed to maintain
3.29
system boundary
boundary based on a set of criteria specifying which processes or sites are part of the system under study
[5]
[SOURCE: ISO 14050:2020 , 3.6.8]
3.30
technically feasible
following an existing and operable route to obtain the output (3.22) or part of the output from the input(s)
(3.18) with specified characteristics (3.28) within the system boundary (3.29)
3.31
transferrable instrument with entitlement to claim
TIEC
administrative record (3.3) that is issued, tracked, retired or retained within a book and claim system,
the ownership of which confers the unique right to claim consumption or use of specified characteristics (3.28)
Note 1 to entry: Prior to retirement, TIECs can be bought, sold, transferred between organizations (3.21), or retained
on behalf of other organizations.
Note 2 to entry: In some book and claim systems, certificate is used as a synonym for TIEC.
3.32
transportation
movement of goods from one location to another performed by modes, such as air, rail, road, water, cable,
pipeline and space and the field comprises the attributes of infrastructure, vehicles, and operations
[10]
[SOURCE: ISO 26683-2:2013 , 3.30]
3.33
unit
standard quantity of specified characteristics (3.28), by which other quantities can be expressed
ISO/FDIS 13662:2025(en)
4 Differentiation between chain of custody models
4.1 General
As described in ISO 22095, the mass balance model is a chain of custody model in which materials
or products with specified characteristics are mixed with materials or products without some or all of these
characteristics. A claim on a part of the output, corresponding to a proportion of the input, is made as a
result of the application of the mass balance model.
Two implementation methods are possible according to ISO 22095:2020, 5.4.2.1:
a) the rolling average percentage method, and
b) the credit method.
ISO 22095 describes and sets the key properties of the chain of custody models: identity preserved,
segregated, controlled blending, mass balance, and book and claim.
This clause provides a description of the differences between the controlled blending, mass balance, and
book and claim models. It is intended to help users of this document to determine either which chain of
custody model is adequate for their system, or whether they selected the appropriate model for their system.
Item and market-based expectations are defined in ISO 22095:2020, 4.3.
Market-based expectations are satisfied under the controlled blending, mass balance and book and claim models.
Item-based expectations are satisfied only by the controlled blending model.
Table 1 provides a technical description of key differences between chain of custody models.
Table 1 — Technical description of key differences between chain of custody models
Entry Question Controlled blending Mass balance model Book and claim model
model
1 Is there a TIEC or credit system No Rolling average per- Yes
in place? centage method: No
Credit method: yes
2 What are the applicable geo- Product or production Process, site, multiple Physical region, de-
graphical system boundaries? process sites, or transportation lineated network, or
process market
3 Are item-based expectations Yes, for the percentage No No
satisfied? with specified charac-
teristics
4 Are the inputs with specified Yes No No
characteristics physically pres-
ent in the output or part of the
output with specified character-
istics at all times?
5 Can TIECs or credits be trans- No No Yes
ferred between organizations
separately from physical materi-
al or product?
6 Is physical separation of material Yes, for the part No No
or product required to ensure with the specified char-
the specified characteristics are acteristics
physically present in the output?
7 Is it required that the specified Yes No No
characteristics be present in the
output in a known proportion?
ISO/FDIS 13662:2025(en)
4.2 Differences between the mass balance model and the controlled blending model
4.2.1 Credits and TIECs — Entries 1 and 5
In the mass balance model, depending on the implementation method, a credit system may be applied,
whereas in the controlled blending model, a credit system cannot be applied.
4.2.2 Geographical system boundary — Entry 2
For the mass balance model, the geographical system boundary can be a process, site, multiple sites or
transportation process.
In the controlled blending model, the system boundary is defined in such a way that the proportion of
specified characteristics in all parts of the outputs can be guaranteed at all times.
4.2.3 Item-based expectations — Entry 3
In the mass balance model, item-based expectations are not satisfied, because physical presence of specified
characteristics in the output is not a requirement.
In contrast, in the controlled blending model, item-based expectations are satisfied and a known proportion
of specified characteristics within all parts of the final output is guaranteed at all times.
4.2.4 Expectation of physical presence — (Entry 4)
In the mass balance model, it is not required that the set of specified characteristics be physically present in
the output at all times.
In contrast, in the controlled blending model, inputs with specified characteristics are kept physically
separate until they are mixed with other inputs without that set of specified characteristics to ensure the
specified characteristics are physically present in the output, at all times.
4.2.5 Physical separation of material or products — Entries 6 and 7
In the mass balance model, physical separation of materials or products is not required.
In the controlled blending model, inputs with specified characteristics are kept physically separate until
they are mixed with other inputs without that set of specified characteristics to ensure the specified
characteristics are physically present in the output. Similarly, the outputs with specified characteristics are
kept separate from the outputs without that set of specified characteristics.
4.3 Differences between the mass balance model and the book and claim model
4.3.1 Credits and transferrable instruments with entitlement to claim (TIEC) — Entries 1 and 5
For the credit method of the mass balance model, specified characteristics are represented as credits in
the system boundary. Specified characteristics may not be transferred between organizations separately
from physical material or product. Credits may only be transferred within the mass balance model system
boundary with physical material or product, except when the conditions of site-to-site credit transfer (see
6.2.3.2) are met.
Credits are not used in the rolling average percentage method of the mass balance model.
In the book and claim model, specified characteristics are represented by TIECs. TIECs may be transferred
between organizations separately from physical material or product.
ISO/FDIS 13662:2025(en)
4.3.2 Geographical system boundary — Entry 2
Geographical system boundaries for the mass balance model are defined as a process, site, multiple sites,
or transportation process.
Geographical system boundaries for the book and claim model are defined as a physical region, delineated
network, or market.
4.3.3 Administrative document flow and physical material or product flow — Entry 5
In the mass balance model, the administrative document is connected to the physical flow of material or
product when the custody of this material or product is transferred from one organization to another
through the supply chain.
In the book and claim model, TIECs are issued as administrative records to represent specified characteristics
which may be decoupled from the physical flow of material or product and sold or transferred between
organizations separately. However, at some point prior to TIEC issuance, there is a connection between the
physical material or product and the specified characteristics represented by the TIEC.
5 Requirements for mass balance chain of custody model
5.1 General
As described in ISO 22095, the mass balance model is a chain of custody model in which materials or products
with specified characteristics are mixed or co-processed to a defined criteria with materials or products
without some or all of these characteristics. A claim on part of the output, corresponding to a proportion of
the input, is made as a result of application of the mass balance model. The mass balance model can also be
applied to energy inputs and outputs.
The mixing or co-processing of materials or products with specified characteristics with materials
or products without some or all of these characteristics can occur throughout all stages of the supply chain
from production and processing to transportation and trading.
NOTE Mixing and co-processing includes activities where supply chain actors may not convert mass balanced
material (for example transportation and trading).
Strict documentation management shall be maintained where the mass balance model is applied.
Each organization active in the chain of custody at each stage of the supply chain shall maintain its own
organizational mass balance model (see Figure 1).
The mass balance model system boundary shall be defined within each organization active in the chain
of custody. The mass balance model system boundary can be defined on a process, site, multiple sites or
transportation process (see 5.3). The mass balance system shall be under the control, or under a common
management system, of one organization.
Figure 1 — Mass balance model system, credit method, boundaries in a value chain context
ISO/FDIS 13662:2025(en)
If the custody of the material or product with specified characteristics is transferred between organizations
active in the chain of custody, the material or product with specified characteristics leave the system
boundary of the organization transferring custody to the receiving organization, and the physical flow of
the material or product shall be connected to the administrative document flow, as described in Figure 1.
Outsourced operations, as described in ISO 22095:2020, 6.11, are part of the organization’s mass balance
model system boundary and shall be included in the chain of custody of the organization. If materials or
products are transferred between organizations as part of an outsourced operation, they do not leave the
system boundary and custody shall not be transferred between organizations. For outsourced operations, a
transfer of administrative documents is not required.
Organizations applying the mass balance model shall balance materials or credits, as described in 5.6, within
the geographical system boundary and balancing period.
As described in ISO 22095:2020, 5.4.1.2, the requirements setter shall consider and document relevant
minimum requirements for all inputs with specified characteristics to the chain of custody system based on
relevant risks.
NOTE Examples of relevant risks include child labour, forced labour, working conditions, environmental impacts.
The requirements setter shall establish the process for communicating and transferring mass balance model
claims for outputs with specified characteristics. If a requirements setter chooses to use a designation
system, they shall use the designation system in Annex C to communicate the claim.
Organizations active in a mass balance chain of custody system shall apply the requirements in
ISO 22095:2020, 6.1 to 6.12.
5.2 Set-up of a mass balance system
A chain of custody system is identified as a mass balance model if the system fulfils the requirements for the
mass balance model as described in 5.1. Setting up a mass balance system shall include the following steps.
See Annex A as an example.
1) Define the specified characteristics to be tracked in the mass balance system.
The requirements setter shall determine the specified characteristics or credits which will be attributed
and tracked.
2) Define the operational set-up.
Within the mass balance system boundary, the operational set-up shall be considered.
The requirements setter shall determine whether a physical link between the material flows of inputs with
specified characteristics and the outputs within the mass balance system boundary.
NOTE 1 Transportation and warehousing are considered as a physical link.
NOTE 2 If the site-to-site credit transfer (see 6.2.3.2) is applied, there is no physical link between sites.
The organization shall consider what route or processes are involved and where inputs with specified
characteristics will enter the mass balance system boundary and outputs with specified characteristics will
exit the same system boundary.
The organization shall confirm whether or not there is the possibility of physical presence of the inputs with
specified characteristics.
Possibility of physical presence means that there is a chance that parts of the inputs with specific
characteristics are physically present in the outputs or part of the outputs as the input with specified
characteristics is located somewhere within the system boundary and that parts of the inputs can move
through that system to become outputs.
ISO/FDIS 13662:2025(en)
The input with specified characteristics shall enter the system boundary and shall be physically present
within the system boundary.
3) Define the mass balance model system boundary.
a) Define the geographical area of the mass balance model system boundary.
Considering the operational set-up, the requirements setter shall define the mass balance model system
boundary based on the geographical area of the relevant operational set-up as a process, site, multiple
sites, or transportation process system boundary.
b) Define the balancing or claim period of the mass balance model system boundary.
Considering the nature of the operational set-up, the requirements setter shall define the balance (credit
method) or claim period (rolling average method), the timeframe in which the credits or specified
characteristics shall be balanced.
4) Define implementation method.
The requirements setter shall determine the implementation method (rolling average percentage method or
credit method) being used (see 6.1 and 6.2).
5) Define attribution principles.
The requirements setter shall determine the attribution principles based on the set-up of the mass balance
system and the implementation method (see 6.1 and 6.2).
6) Set up a credit system (only for credit method).
In case of the credit method, a credit accounting system shall be set up and maintained and should accurately
reflect the credit balance at all times (see 6.2.1) and shall be balanced at the end of the balancing period. The
conversion factor (see 5.7) shall be considered when calculating the amount of credits entering or being
withdrawn from the credit account.
7) Review of the mass balance system.
The quantity of credits shall be calculated at the end of a balancing period and shall be greater than or equal
to zero. Credits may be transferred to the next balancing period if credits are still valid (see 6.2.3.3).
Subclause C.1 provides a designation system for mass balance systems based on the considerations of
this Clause. The designation system helps requirements setters and users of a chain of custody model to
transparently design and manage a mass balance system meeting their expectations and needs, and to
communicate the design choices made.
Generic examples demonstrating the use of the designation system (see Annex C) can be found in Annex D.
The mass balance system credit method is a method where the appropriate quantity of credits are
created when an input with a specified characteristic enters the system boundary. Therefore, specified
characteristics exist in the system boundary only as credits up to the point they are attributed to an output
or part of an output (see Figure 2).
ISO/FDIS 13662:2025(en)
Key
1 utilities (steam, electricity, others)
2 losses (waste, emission, other)
a
Credits may be carried into a system boundary independent of physical material flow using site-to-site
credit transfer.
Figure 2 — Differentiation of credits and specified characteristics in a mass balance system
credit method
The mass balance system rolling average method is a method where credits, and a credit account, are not
utilized. The specified characteristics are maintained in the system boundary. The quantity of specified
characteristics received within a claim period shall be attributed by the end of that claim period and shall
not be transferred to the next claim period. Specified characteristics are attributed to outputs when the
rolling average method is used.
5.3 System boundary
5.3.1 General requirements
The requirements setter shall define:
— the specified characteristics to be monitored, and to be passed down the supply chain; and
— the system boundary to monitor specified characteristics of the input and output entering and leaving
the mass bala
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Chain of custody — Mass balance — Requirements and guidelines
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ISO/FDIS 13662:2025(en)
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
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may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
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ISO/DISFDIS 13662:2025(en)
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Contents
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Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Differentiation between chain of custody models . 6
5 Requirements for mass balance chain of custody model . 9
6 Mass balance model implementation methods . 18
7 Claims and communication . 21
Annex A (informative) Set-up of a mass balance model . 25
Annex B (informative) Examples for setting up a credit account and utilization of conversion
and consumption factors for the credit method . 28
Annex C (normative) Designation system for mass balance chain of custody model . 36
Annex D (informative) Examples for designation system for mass balance model . 9
Bibliography . 19
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Differentiation between chain of custody models . 5
4.1 General . 5
4.2 Differences between the mass balance and the controlled blending model . 7
4.3 Differences between the mass balance and the book and claim model . 7
5 Requirements for mass balance chain of custody . 8
5.1 General . 8
5.2 Set-up of a mass balance system. 9
5.3 System boundary . 10
5.4 Time period . 11
5.5 Material and credit reconciliation . 12
5.6 Conversion and consumption factor . 13
5.7 Avoidance of double counting in mass balance systems . 14
5.8 Returned materials and products . 14
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6 Mass balance implementation methods . 15
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6.1 Mass balance rolling average percentage method . 15
6.2 Mass balance credit method . 15
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7 Claims and communication requirements . 18
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7.1 Claims . 18
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7.2 Communication . 19
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Annex A (informative) Set-up of a mass balance system . 21
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ISO/FDIS 13662:2025(en)
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Annex B (informative) Examples conversion and consumption factor for the credit method . 22
Annex C (normative) Designation system for mass balance chain of custody . 28
Annex D (informative) Examples for designation system for mass balance chain of custody . 35
Bibliography . 41
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ISO/DISFDIS 13662:2025(en)
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Foreword
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ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for identifying any or all such
patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
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This document was prepared by Technical Committee ISO/TC 308, Chain of custody.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html.
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© ISO 2025 – All rights reserved
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v
ISO/FDIS 13662:2025(en)
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Introduction
The mass balance model is one of five chain of custody models outlined in ISO 22095. A mass balance model
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offers different methods for organisations to mix or co-process inputs with and without specified
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characteristics while transparently documenting the movement of the inputs and their specified
characteristics. This is to ensure that the credits or specified characteristics are appropriately accounted for
and attributed to outputs within the same system boundary.
NOTE Mixing and co-processing includes activities where those in the value chain (i.e. brokers) do not physically
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mix or co-process mass balanced material or products.
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A mass balance model is ideally suited for certain situations, such as when identity preserved, segregated, or
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controlled blending chain of custody models are not feasible. For instance, in some supply chains, materials or
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products with specified characteristics are mixed or co-processed with materials or products without
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specified characteristics. New materials or products are then produced. It is not possible to distinguish which
of these new materials or products were derived from inputs with, and without, specified characteristics.
However, the quantity of input with specified characteristics, such as renewable feedstock or fair trade labour
practices, are in the system. Therefore, it becomes appropriate to pass forward those specified characteristics
through a chain of custody model. Many industries currently use a mass balance model including
transportation, agriculture, textiles, forestry, construction, chemicals, metals, steel, energy, glass, plastics,
organics and inorganics.
However, the mass balance model may be applied differently in the market based on the criteria selected. This
may create confusion and reduce its credibility among consumers, policy makers, standard setters, and other
stakeholders. This document provides guidance to explain the mass balance chain of custody model and limit
the risk of confusion on mass balance model communication (for example claims) in the marketplace and
throughout the value chain.
This document helps organizations outline technical choices, define system boundaries, and specify methods
of attribution. In addition, it provides guidance on communication and claims.
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vi
DRAFT International Standard ISO/DIS 13662:2025(en)
Chain of custody — Mass balance — Requirements and guidelines
1 Scope
This document provides requirements and guidelines for the application of the mass balance chain of
custody model, as defined in ISO 22095, to any material or product flow within mass balance systems,
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including how to attribute specified characteristics to flows of such processes.
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This document provides requirements and guidelines for the following matters, amongst others:
— — differentiations from controlled blending and book and claim models;
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— — general requirements for organizations active in a mass balance chain of custody model;
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— — system boundaries including geography and time;
— — conversion factors;
— — the rolling average percentage method;
— — the credit method;
— — transparency, communication, and claims.
2 Normative references
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The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any amendments)
applies.
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ISO 22095:2020, Chain of custody — General terminology and models
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3 Terms and definitions
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For the purposes of this document, the terms and definitions given in ISO 22095 and the following apply.
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ISO and IEC maintain terminological databases for use in standardization at the following addresses:
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— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
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— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
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3.1 3.1
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administrative document
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documentation that uniquely identifies the entitlement to claim the ownership of the specified
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characteristics (3.28)(3.28) of materials or products at the respective point in the chain of custody
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3.2 3.2
administrative document flow
process that uniquely identifies the entitlement to the claim of ownership and the transfer of the claim
of ownership of the specified characteristics (3.28)(3.28) of materials or products through the chain of
custody
3.3 3.3
administrative record
documentation or guarantee that warrants unique ownership of the entitlement to claim
the consumption or use of specified characteristics (3.28)(3.28) at a point in the chain of custody
Note 1 to entry: “Specified characteristics” is defined in ISO 22095:2020, 3.2.5 and “chain of custody”
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is defined in ISO 22095:2020, 3.1.1.
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3.4 3.4
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administrative record flow
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movement or transfer of unique ownership of the entitlement to claim consumption or use of specified
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characteristics (3.28)(3.28) within the chain of custody
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3.5 3.5
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associated information
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information related to the material or product such as description, quality, assurance, or life cycle
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related data
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3.6 3.6
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attribution
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assignment of credits (3.13)(3.13) (credit method) or specified characteristics (3.28)(3.28) (rolling
numbers
average method) to outputs (3.22)(3.22) or part of the outputs
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3.7 3.7
numbers
balancing period
time frame when the credits (3.13)(3.13) associated with inputs (3.18)(3.18) and outputs (3.22)(3.22)
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with specified characteristics (3.28)(3.28) are balanced in the temporal boundaries of the system Asian text, Adjust space between Asian text and
numbers
3.8 3.8
book and claim model
chain of custody model in which the administrative record flow (3.4)(3.4) is not necessarily connected
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Note 1 to entry: This chain of custody model is also referred to as "certificate trading” or "credit trading”. stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
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Note 2 to entry: Within a book and claim system, a Transferable Instrument with Entitlement to Claim (TIEC)
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represents the right to claim specified characteristics (3.28),(3.28), which can be bought, sold, transferred between
organizations (3.21),(3.21), or retained on behalf of other organizations. The term “certificates” is used in ISO Formatted: Default Paragraph Font
22095, whereas the term ”TIEC” is used here for consistency. TIEC is defined in 3.31.3.31.
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[SOURCE: ISO 22095:2020, 3.3.5, modified — In Note 1 to entry the wording has been modified, Note 2
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to entry has been added.]
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3.9 3.9
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claim
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Note 1 to entry: Information can be any message or representation, including textual, pictorial, graphic or
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symbolic representation in any form in the context of a commercial communication.
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Note 2 to entry: A claim can be made using various means or channels for example on the product or physically
attached to the product or physical or virtual information about the product.
[SOURCE: ISO 22095:2020, 3.5.10, modified — Notes 1 and 2 to entry have been added.]
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3.10 3.10
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claim period
time frame when claims (3.9)(3.9) can be made on materials or products
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3.11 3.11
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consumption factor
specification of conversion factor (3.12)(3.12) that considers individual steps and/or individual inputs
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(3.18)(3.18) in a system boundary with one or more inputs and/or one or more steps, rather than
aggregated over steps and/or inputs, which results in a single overall conversion factor
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Note 1 to entry: In the case of a single input and single step process, the conversion factor and consumption
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factor would be equal.
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conversion factor
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ratio which is used to determine the quantity of output (3.22)(3.22) or part of the output with specified
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characteristics (3.28)(3.28) that can be obtained from the quantity of the input (3.18)(3.18) with
numbers
specified characteristics, taking into account any losses
3.13 3.13
credit
representation of the quantity of units (3.33)(3.33) available for attribution with entitlement to claim
the ownership of specified characteristics (3.28)(3.28)
3.14 3.14
credit account
system used by organizations (3.21)(3.21) to record and track the credits (3.13)(3.13) associated with
specified characteristics (3.28)(3.28)
3.15 3.15
destructive process
processing for the purpose of the recovery of materials without preserving the original product
or component
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EXAMPLE Disintegration (crushing, shredding, milling, grinding), concentration (separation, non-
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destructive depollution, homogenization), refining and re-melting.
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[11][ ]
[SOURCE: ISO 59014:2024, 0 , 3.6, modified — ‘process to obtain secondary materials without any
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intent of’ deleted, replaced with ‘processing for the purpose of the recovery of materials without’;
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Example modified: ‘destructive depollution’ to ‘non-destructive depollution’.]
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3.16 3.16
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double counting
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accounting for inputs (3.18)(3.18) or outputs (3.22)(3.22) or specified characteristics (3.28)(3.28) more
than once
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[5][ ]
[SOURCE: ISO 14050:2020, 0 , 3.5.25]
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3.17 3.17
evaluation period
time frame when the performance of the chain of custody system is monitored, measured, analysed
and evaluated by conducting audits to assess the performance of the chain of custody system procedures
and the conformance with all applicable requirements
3.18 3.18
input
material or product that enters a chain of custody system boundary (3.29)(3.29)
Note 1 to entry: Input can be used at any stage of the supply chain.
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Note 2 to entry: Input can also include reused and recycled materials or products.
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Note 3 to entry: Input can have associated information (3.5),(3.5), such as specified characteristics (3.28).(3.28).
3.19 3.19
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mass balance model
Asian text, Adjust space between Asian text and
chain of custody model in which materials or products with a set of specified characteristics (3.28)(3.28) numbers
are mixed or co-processed according to defined criteria with materials or products without that set of
characteristics
Note 1 to entry: The proportion of the input (3.18)(3.18) with specified characteristics might only match the
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initial proportions on average and will typically vary across different outputs (3.22).(3.22).
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Note 2 to entry: The mass balance model establishes the relation between inputs and outputs with specified
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characteristics and the distribution of those inputs and outputs via attribution (3.6).(3.6).
Note 3 to entry: For the mass balance model, two implementation methods are specified: rolling average
percentage method and credit method.
Note 4 to entry: In the mass balance model, the specified characteristics cannot be transferred between different
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organizations (3.21)(3.21) independent of physical materials or products.
[SOURCE: ISO 22095:2020, 3.3.4, modified — Note 2 to entry has been modified, Notes 3 and 4 to entry
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have been added.]
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3.20 3.20
non-proportional attribution
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assignment of credits (3.13)(3.13) to one or more outputs (3.22)(3.22) irrespective of the proportion of
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the individual outputs with respect to the total output
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3.21 3.21
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organization
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entity or group of people and facilities with an arrangement of responsibilities, authorities
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
and relationships and identifiable objectives
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Note 1 to entry: An organization can encompass multiple (production/geographical) sites.
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Note 2 to entry: An organization includes a corporate group defined as a number of consolidated legal entities
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guided by a parent company.
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[9][ ]
[SOURCE: ISO 26000:2010, 0 , 2.12, modified — Note 2 to entry has been added.]
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3.22 3.22
output
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material or product that leaves a chain of custody system boundary (3.29)(3.29)
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
Note 1 to entry: Output can be created at any stage of the supply chain.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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ISO/DIS 13662:2025(en)
Note 2 to entry: Output might include other products resulting from production processes.
Note 3 to entry: Product covers material or energy products.
3.23 3.23
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primary data
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quantified value of a unit (3.33)(3.33) process (3.24)(3.24) or an activity obtained from a direct numbers
measurement, or a calculation based on direct measurements at the original source
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[5][ ]
[SOURCE: ISO 14050:2020, 0 , 3.6.34]
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3.24 3.24
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process
set of interrelated or interacting activities that use inputs (3.18)(3.18) to deliver an intended output
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(3.22)(3.22)
Note 1 to entry: A process can include provision of services, such as storage or transportation (3.32).(3.32).
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Note 2 to entry: Technical operations of processes include continuous process, semi-batch, and batch.
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Note 3 to entry: A process can also be a discrete process with a discrete time boundary such as production
of a fashion collection or a furniture line.
[1][ ]
[SOURCE: ISO 9000:2015, 0 , 3.4.1, modified — The word “result” has been replaced by “output”.
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Notes 1 to 6 to entry have been deleted. Notes 1, 2 and 3 to entry have been added.]
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3.25 3.25
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proportional attribution
assignment of credits (3.13)(3.13) to one or more outputs (3.22)(3.22) according to the proportion of
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the individual outputs with respect to the total output
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3.26 3.26
requirements setter
person, organization (3.21),(3.21), regulator or independent third-party program operator that
specifies requirements for a particular chain of custody
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Note 1 to entry: Organizations active in the chain of custody can also act as the requirements setter.
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Note 2 to entry: The mass balance system is defined by the requirements setter.
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[SOURCE: ISO 22095:2020, 3.4.3, modified — Notes 1and 2 to entry have been added.]
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3.27 3.27
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similar in nature
material, products, or concepts that share common characteristics e.g. functionalities, qualities,
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composition or attributes, making them alike in fundamental aspects
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3.28 3.28
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specified characteristic
numbers
set of product and/or production characteristics that the chain of custody is designed to maintain
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3.29 3.29 Asian text, Adjust space between Asian text and
numbers
system boundary
boundary based on a set of criteria specifying which processes or sites are part of the system
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under study
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numbers
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ISO/FDIS 13662:2025(en)
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[5][ ]
[SOURCE: ISO 14050:2020, 0 , 3.6.8]
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3.30 3.30
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technically feasible
following an existing and operable route to obtain the output (3.22)(3.22) or part of the output from the
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input(s) (3.18)(3.18) with specified characteristics (3.28)(3.28) within the system boundary (3.29)(3.29)
3.31 3.31
transferrable instrument with entitlement to claim
TIEC
administrative record (3.3)(3.3) that is issued, tracked, retired or retained within a book and claim
system, the ownership of which confers the unique right to claim consumption or use of specified
characteristics (3.28)(3.28)
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Note 1 to entry: Prior to retirement, TIECs can be bought, sold, transferred between organizations (3.21),(3.21),
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
or retained on behalf of other organizations.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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Note 2 to entry: In some book and claim systems, certificate is used as a synonym for TIEC.
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numbers
3.32 3.32
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transportation
movement of goods from one location to another performed by modes, such as air, rail, road, water,
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cable, pipeline and space and the field comprises the attributes of infrastructure, vehicles,
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and operations
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[10][ ]
[SOURCE: ISO 26683-2:2013, 0 , 3.30]
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3.33 3.33
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unit
stops: Not at 0.71 cm
standard quantity of specified characteristics (3.28),(3.28), by which other quantities can be expressed
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4 Differentiation between chain of custody models
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4.1 General
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As described in ISO 22095, the mass balance model is a chain of custody model in which materials
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or products with specified characteristics are mixed with materials or products without some or all of
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these characteristics. A claim on a part of the output, corresponding to a proportion of the input, is made
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as a result of the application of the mass balance model.
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Two implementation methods are possible according to ISO 22095:2020, 5.4.2.1:
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b, c, … + Start at: 1 + Alignment: Left + Aligned at: 0 cm
a) a) the rolling average percentage method, and
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b) b) the credit method.
numbers, Tab stops: Not at 0.7 cm + 1.4 cm + 2.1 cm
+ 2.8 cm + 3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3
ISO 22095 describes and sets the key properties of the chain of custody models: identity preserved,
cm + 7 cm
segregated, controlled blending, mass balance, and book and claim.
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This clause provides a description of the differences between the controlled blending, mass balance, and
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book and claim models. It is intended to help users of this document to determine either which chain of Adjust space between Asian text and numbers
custody model is adequate for their system, or whether they selected the appropriate model for their
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system.
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Item and market-based expectations are defined in ISO 22095:2020, 4.3.
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ISO/DIS 13662:2025(en)
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Market-based expectations are satisfied under the controlled blending, mass balance and book and
claim models. Formatted
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Item-based expectations are satisfied only by the controlled blending model.
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Table 1Table 1 provides a technical description of key differences between chain of custody models.
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Table 1 — Technical description of key differences between chain of custody models
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Entr Question Controlled Mass balance Book and claim
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y blending model model model
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1 Is there a TIEC or credit No Rolling average Yes
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system in place? percentage method:
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No
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Credit method: yes
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2 What are the applicable Product or Process, site, Physical region,
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geographical system production process multiple sites, delineated network,
boundaries? or transportation or market
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process
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3 Are item-based expectations Yes, for the No No
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satisfied? percentage with
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specified
characteristics
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4 Are the inputs with specified Yes No No
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characteristics physically
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present in the output or part
of the output with specified Formatted
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characteristics at all times?
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5 Can TIECs or credits be No No Yes
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transferred between
organizations separately from Formatted
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physical material or product?
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6 Is physical separation Yes, for the part No No
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of material or product with the specified
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required to ensure the characteristics .
specified characteristics are
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physically present in the
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output? .
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7 Is it required that the Yes No No
specified characteristics be
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present in the output in a
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known proportion?
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4.2 Differences between the mass balance model and the controlled blending model
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4.2.1 Credits and TIECs — Entries 1 and 5
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In the mass balance model, depending on the implementation method, a credit system may be applied,
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whereas in the controlled blending model, a credit system cannot be applied.
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ISO/FDIS 13662:2025(en)
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4.2.2 Geographical system boundary — Entry 2
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For the mass balance model, the geographical system boundary can be a process, site, multiple sites or
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transportation process.
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In the controlled blending model, the system boundary is defined in such a way that the proportion of
specified characteristics in all parts of the outputs can be guaranteed at all times.
4.2.3 Item-based expectations — Entry 3
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In the mass balance model, item-based expectations are not satisfied, because physical presence of
stops: Not at 0.71 cm + 0.99 cm + 1.27 cm
specified characteristics in the output is not a requirement.
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In contrast, in the controlled blending model, item-based expectations are satisfied and a known
proportion of specified characteristics within all parts of the final output is guaranteed at all times.
4.2.4 Expectation of physical presence — (Entry 4)
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In the mass balance model, it is not required that the set of specified characteristics be physically present
stops: Not at 0.71 cm + 0.99 cm + 1.27 cm
in the output at all times.
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In contrast, in the controlled blending model, inputs with specified characteristics are kept physically
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separate until they are mixed with other inputs without that set of specified characteristics to ensure
the specified characteristics are physically present in the output, at all times.
4.2.5 Physical separation of material or products — Entries 6 and 7
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In the mass balance model, physical separation of materials or products is not required.
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stops: Not at 0.71 cm + 0.99 cm + 1.27 cm
In the controlled blending model, inputs with specified characteristics are kept physically separate until
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they are mixed with other inputs without that set of specified characteristics to ensure the specified
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characteristics are physically present in the output. Similarly, the outputs with specified characteristics
are kept separate from the outputs without that set of specified characteristics.
4.3 Differences between the mass balance model and the book and claim model
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4.3.1 Credits and transferrable instruments with entitlement to claim (TIEC) — Entries 1
stops: Not at 0.71 cm
and 5
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For the credit method of the mass balance model, specified characteristics are represented as credits in
stops: Not at 0.71 cm + 0.99 cm + 1.27 cm
the system boundary. Specified characteristics may not be transferred between organizations
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separately from physical material or product. Credits may only be transferred within the mass balance
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model system boundary with physical mater
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