Identity Preserved, Segregated, Mass Balance and Book-and-Claim: What Each Model Proves
Compare identity-preserved, segregated, mass-balance and book-and-claim chain-of-custody models, including what each can and cannot prove about a product claim.
Direct answer
Identity preserved keeps a specified source or input identity distinct through the chain. Segregated keeps qualifying material physically separate from non-qualifying material while allowing qualifying material to be combined within the scheme's rules.
Controlled blending allows specified and other material to be physically combined in controlled proportions. Mass balance accounts for specified characteristics across defined inputs and outputs and permits allocation under the applicable rules. Book-and-claim separates the claim transaction from the physical flow to a greater degree, using a governed accounting or certificate system.
Chain-of-custody models do not all make the same promise about the physical relationship between an input and a downstream product. The model tells you how a specified characteristic or claim is connected through the chain, not whether the underlying characteristic is true simply because a custody system exists.
The practical question is therefore not “is this traceable?” It is: what physical or accounting connection does this model support, at what scope and under which claim rules?
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Model comparison
| Model | Relationship it is designed to preserve | What a downstream record can support | What it must not be turned into |
|---|---|---|---|
| Identity preserved | A specified source or input remains separately identifiable | A strong physical link to the identified source/input across the covered chain | Proof of steps outside the covered chain |
| Segregated | Qualifying material is kept apart from non-qualifying material | Physical presence of qualifying material under the scheme, without necessarily preserving one original source | A claim that every unit came from one named source |
| Controlled blending | Specified and other material are physically mixed in controlled proportions | A claim tied to the governed physical blend and its rules | Identity preservation of the specified input |
| Mass balance | Specified characteristics are accounted for across inputs and outputs within a defined system boundary | An allocated claim supported by the mass-balance system | Atom-level provenance or proof that the attributed characteristic is physically present in one particular item |
| Book-and-claim | The characteristic or benefit is accounted for separately from the physical flow under a governed system | A claim or certificate allocation permitted by that system | A statement that the claimed material physically travelled into the purchased item |
These are model-level distinctions. A sector scheme can add tighter controls, different terminology or narrower claim language. The governing law or scheme decides whether a particular claim is permissible.
Physical relationship versus allocated claim
The easiest mistake is to put all five models on a scale from “strong” to “weak”. That is not the useful comparison.
They preserve different relationships. Identity-preserved and segregated approaches maintain a direct physical relationship. Controlled blending maintains a physical mixture under governed proportions. Mass balance permits accounting and allocation within a defined system. Book-and-claim permits an even more separated relationship between physical flow and the claim instrument.
That does not make an allocated claim automatically invalid. It means the wording of the claim must match what the model supports.
If a mass-balance system allocates a specified characteristic to an output, the evidence can support the allocation under that system. It does not follow that the same characteristic can be physically located in the atoms of the particular downstream unit. ISO 22095-2:2026 is now the dedicated international standard for mass-balance chain of custody. ISO 22095-3:2026 separately covers book-and-claim and explicitly distinguishes it from mass balance.
Chain of custody is not the underlying proof
ISO's published description of the general framework is unusually useful on this boundary. ISO 22095:2020 says a chain-of-custody system is not, on its own, enough to support claims about an organisation's materials or products.
The reason is simple. Custody records govern the relationship between a specified characteristic, inputs and outputs. They do not create the characteristic. If a recycled-content claim begins with a value that was never established, perfect custody records can carry the unsupported value perfectly.
You therefore need two questions, not one:
- What establishes the characteristic at the point it enters the system?
- What custody model and records govern how that characteristic may travel or be allocated downstream?
A certificate can be relevant to either question, but its title alone does not tell you which one it answers.
What evidence is still needed?
Whatever model is used, a downstream business still needs enough evidence to understand the subject and scope of the claim. In practice that means checking at least:
- the product, material or flow to which the record applies
- the organisation or site within scope
- the relevant accounting, production or certificate period
- the specified characteristic being carried
- the model or scheme rules used
- the quantity or allocation where that is material
- the identifiers that bind the evidence to the downstream record
- any exclusions, conversions or limitations that change the meaning of the claim.
This is where an apparently valid certificate can fail operationally. A record may be genuine but apply to a facility rather than a product, a product family rather than a delivered batch or an accounting period that does not cover the transaction.
A recycled-content example
Suppose a business buys material carrying a 60% recycled-content allocation under a mass-balance system. The arithmetic can be valid within the scheme while the physical composition of a particular unit is different. The publication question is not “is 60% real?” in the abstract. It is “what exactly does the scheme permit this 60% to describe?”
If the scheme permits an allocated mass-balance claim, the business can retain that evidence as an allocation at the scheme's defined scope. It should not silently convert it into a statement that 60% of the atoms in this exact unit came from recovered material.
The specialist question of what a recycled-content certificate lets you assert belongs with recycled-content claim evidence. This page owns the generic custody-model distinction, not the field-specific publication rule.
What happens when products split, mix or transform?
Custody becomes harder at transformations because the subject of the evidence can change. One input lot can become several outputs, several inputs can become one output and an accounting allocation may have to be reconciled across a period.
The model tells you the rules for preserving or allocating the specified characteristic. Your data architecture still needs reliable identities and scope so the resulting claim is attached to the right descendant, quantity and period.
If the harder question is how mapping, provenance, traceability and chain of custody differ before you choose a model, see the broader supply-chain vocabulary comparison.
What the model cannot prove
A custody model does not automatically prove:
- that the initial characteristic was measured or verified correctly
- that a document applies to the exact item in front of you
- that a voluntary scheme makes a claim legally permissible in every market
- that a mass-balance allocation is atom-level provenance
- that book-and-claim means the claimed physical material travelled through the buyer's product
- that a complete custody record is the same thing as a complete DPP event history.
Those are separate evidence, scope and legal questions.
What would change this page
ISO 22095:2020 remains published and is currently marked to be revised. ISO 22095:2020/Amd 1:2026, ISO 22095-2:2026 and ISO 22095-3:2026 are published. ISO/CD 22095-1 is under development and is not treated as final here. This page should be rechecked when the replacement general framework is published or when a material sector rule changes the permitted claim semantics.
Sources
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