Standards Deep Dive Inside the six-layer system

Data Clean Rooms, PETs & PAIR.

The data collaboration layer: IAB Tech Lab’s Data Clean Room Guidance, PAIR activation, ADMaP attribution, the privacy-enhancing technologies underneath — and the output policy that decides what actually leaves the room.

This is a deep dive inside the six-layer standards system, not a seventh pillar — the deep dives show where those standards become real in specific operating environments. Clean rooms are where the privacy layer’s permissions, the transaction layer’s rails, and the trust layer’s measurement all meet two parties’ first-party data. The standards now cover the room itself, activation out of it, and attribution through it. What no standard covers is the decision every deployment still has to make: what is allowed to leave.

The data clean room collaboration layer — the room constrains the computation; the output policy decides what leaves. DATA CLEAN ROOMS — PETS, PAIR & OUTPUT POLICY INPUTS — WHAT ENTERS THE ROOM OUTPUTS — WHAT ASKS TO LEAVE Advertiser data — the advertiser’s own first-party records and identifiers. In PAIR, join keys are hashed and encrypted before anything is matched; raw lists are never handed to the other side. advertiser data Publisher data — the publisher’s own first-party audience records. IAB Tech Lab’s clean-room portfolio exists so two first-party datasets can be matched and analyzed without either side exposing raw records to the other. publisher data Match keys — the identifiers a join runs on (emails, IDs), pseudonymized and encrypted. PAIR uses commutative ciphers so keys encrypted by both parties match without decryption back to cleartext. match keys Consent signals — the permissions attached to the underlying data. A clean room does not create a legal basis; the consent and purpose restrictions on inputs still govern what any output may be used for. Validate obligations per market. consent signals Purpose and terms — the contractual agreement: what the collaboration is for, what may be queried, and what may leave. IAB Tech Lab’s Data Clean Room Guidance v1.0 outlines principles and guardrails; the contract makes them enforceable. purpose & terms Private set intersection — compute the overlap of two datasets without either side revealing non-matching records. Named alongside trusted execution environments in ADMaP v1.0 for attribution matching. PSI Differential privacy — calibrated noise so outputs resist isolating individuals. IAB Tech Lab’s PETs Working Group published Differential Privacy Guidance (final PDF posted May 2024) covering ad-tech use cases and privacy-utility tradeoffs. differential privacy Aggregation — reporting in groups rather than rows, with minimum cell sizes. The threshold is a policy decision: small or overlapping cells can still re-identify. aggregation Encryption and hashing — protect data in transit and at rest, and pseudonymize join keys. PAIR’s commutative encryption is the working example: jane@email.com × Ka × Kp equals jane@email.com × Kp × Ka, so matching never requires cleartext. encryption Trusted execution environments — hardware-isolated computation. ADMaP v1.0 names TEEs among its PETs, and PAIR v1.1 includes a “Single DCR with TEE” deployment model. Trust shifts to the hardware and attestation chain — it does not vanish. TEEs The data clean room — IAB Tech Lab’s portfolio (Rearc Addressability and PETs working groups): Data Clean Room Guidance v1.0 (the hub page states v1.0 was released in July 2024), PAIR v1.1 for activation (finalized July 2025), ADMaP v1.0 for attribution (finalized February 25, 2025), and the Differential Privacy Guidance (final May 2024). The stated goal of the 2023 portfolio launch: secure, purpose-limited, privacy-protected data collaboration while minimizing data movement. OPJA, the first interoperability standard, is deprecated and superseded by PAIR. DATA CLEAN ROOM — THE COLLABORATION LAYER match · analyze · measure — without moving or exposing raw data DCR Guidance 1.0 · PAIR 1.1 · ADMaP 1.0 · diff. privacy guidance Aggregate insights — overlap analyses, audience composition, campaign readouts. The default safe shape of a clean-room output: grouped, thresholded, and purpose-bound — if the output policy says so. aggregate insights PAIR activation — matched first-party audiences activated programmatically: encrypted publisher IDs carried in the OpenRTB 2.6 eids object, with an Open PAIR module for Prebid.js. PAIR v1.1 was finalized in July 2025. PAIR activation Attribution — ADMaP v1.0 (Attribution Data Matching Protocol, finalized February 25, 2025) standardizes privacy-centric attribution and conversion measurement between advertisers and publishers using PSI and TEEs on deterministic first-party data. attribution Overlap statistics — match rates and audience overlap counts. Useful, and quietly risky: repeated or differencing queries against overlap stats are a classic re-identification path. Rate limits and logging belong in the output policy. overlap stats Audit trail — who queried, what left, where it went, under which policy version. The evidence layer that makes a clean-room deployment defensible — and the alibi an autonomous workflow needs. audit trail The output gate — every category to the left passes through output policy: thresholds, noise, purposes, destinations, logging. The techniques enforce the policy; they do not write it. output gate The output policy rail under everything: purpose limits, aggregation thresholds, consent carried from inputs to outputs, destination allow-lists, and audit logging. The PETs above enforce these decisions — they do not make them. A clean room without output policy is just a safer room with an unsafe door. OUTPUT POLICY RAIL purpose limits · thresholds · consent · destinations · audit
The clean-room standards landscape: what enters the room, the PETs underneath, the IAB Tech Lab portfolio in the middle, and the output policy rail it all rests on.

A clean room is where two parties who do not trust each other’s infrastructure agree to trust a process.

PETs are techniques. Policy is a decision. A clean room needs both — and only one of them ships in the box.

Interoperability is now a standards question: PAIR for activation, ADMaP for attribution, OPJA deprecated behind them.

The unsafe door

A clean room without output policy is just a safer room with an unsafe door.

Fast read

What it is
A deep-dive guide to data clean room standards: IAB Tech Lab’s Data Clean Room Guidance v1.0, PAIR v1.1 for activation, ADMaP v1.0 for attribution, the privacy-enhancing technologies underneath — and the output policy that decides what actually leaves the room.
What it covers
What a clean room solves and what it does not, PAIR’s commutative matching and OpenRTB 2.6 eids activation, OPJA’s deprecation, PETs in plain language, nine output categories, a twelve-point output policy checklist, and agentic implications.
What it is not
Not a vendor comparison and not a legal-compliance manual. These are guidance documents and protocols — public documentation describes what they standardize, and nothing here makes a deployment compliant by itself.
Why it matters
Agents will query collaboration outputs at machine speed. Whether those outputs stay aggregate, purpose-bound, and logged is decided by output policy — the one layer no clean room ships in the box.
Best for
AdTech, media, agency, brand, retail media, data collaboration, measurement, and privacy leaders building or evaluating clean-room workflows.
Best next read
Privacy & Consent Standards, Measurement & Media Quality, and the Enterprise Data Collaboration playbook.
Orientation

Where clean room standards fit.

Clean rooms are a child of the six-layer system, not a parallel universe. The guidance and interoperability layers are IAB Tech Lab’s — the Rearc Addressability and PETs working groups produced the Data Clean Room Guidance v1.0, PAIR v1.1, ADMaP v1.0, and the Differential Privacy Guidance. Activation lands back on the Core AdTech rails (encrypted IDs in OpenRTB 2.6 eids, an Open PAIR module for Prebid.js); permissions come from the privacy layer and attach to the data, not the infrastructure; and measurement readouts inherit the trust layer’s discipline. The output policy rail at the bottom belongs to no standard at all — it belongs to you.

Where clean room standards sit — between the collaboration two parties intend and the output policy rail that decides what leaves. CLEAN ROOMS IN THE STANDARDS STACK Data collaboration intent — two parties with first-party data, a shared question, and permissions attached to every record. Everything below exists so that intent can be executed without either side exposing raw data to the other. DATA COLLABORATION INTENT first-party data · partner terms · permissions · purpose Clean room guidance — IAB Tech Lab’s Data Clean Room Guidance and Recommended Practices, Version 1.0 (the official hub page states v1.0 was released in July 2024; it first went to public comment in February 2023). It establishes common DCR principles, functions, and privacy-enhancing technologies, plus limitations and guardrails. Guidance, not law — and no v2.0 exists. CLEAN ROOM GUIDANCE DCR Guidance v1.0 — principles · functions · PETs · guardrails Interoperability protocols — PAIR v1.1 (finalized July 2025) standardizes matching and activating a common advertiser–publisher audience; ADMaP v1.0 (Attribution Data Matching Protocol, finalized February 25, 2025) standardizes privacy-centric attribution measurement. OPJA, Tech Lab’s first clean-room interoperability standard, is deprecated and superseded by PAIR — official wording: going forward PAIR will be the designated standard. INTEROPERABILITY PROTOCOLS PAIR 1.1 (activation) · ADMaP 1.0 (attribution) · OPJA deprecated Privacy-enhancing techniques — the machinery: private set intersection, differential privacy (Tech Lab guidance final May 2024), trusted execution environments, aggregation, encryption and hashing. Techniques enforce decisions; they do not make them. There is no single Tech Lab document titled “PETs Guidance” — the published guidance is the Differential Privacy Guidance plus the PETs initiative materials. PRIVACY-ENHANCING TECHNIQUES PSI · differential privacy · TEEs · aggregation · encryption Activation and measurement — where clean-room outputs meet the rails: encrypted publisher PAIR IDs carried in the OpenRTB 2.6 eids object, the Open PAIR module (openPairIdSystem.js) in Prebid.js introduced with v1.1, and aggregate measurement readouts via ADMaP. Public documentation describes prerequisites and adoption goals — validate current support with each partner. ACTIVATION + MEASUREMENT OpenRTB 2.6 eids · Open PAIR Prebid module · aggregate readouts The output policy rail — aggregation thresholds, purpose limits, consent carried from inputs into outputs, re-identification testing against small cells and repeated queries, and audit logging of every export. No standard above sets these numbers for you; the guidance outlines guardrails, and your deployment and contract make them real. OUTPUT POLICY RAIL thresholds · purpose limits · consent · re-identification tests · audit
A deep-dive layer map: clean room guidance and interoperability protocols positioned between the collaboration two parties intend and the output policy rail that decides what leaves.
The honest yes

What a clean room actually solves.

Six things, and they are real. This is why the category exists and why IAB Tech Lab built a standards portfolio around it instead of leaving it to vendor dialects.

  • 01

    Joint analysis, minimal movement

    The point of the portfolio, in IAB Tech Lab’s own 2023 framing: secure, purpose-limited, privacy-protected data collaboration no matter who uses which technology provider — while minimizing data movement. Two parties analyze a shared question without shipping raw datasets to each other.

  • 02

    Matching without cleartext

    PAIR matches first-party identifiers with commutative ciphers: [email protected] × Ka × Kp equals [email protected] × Kp × Ka, so keys encrypted by both parties match without ever decrypting back to cleartext. The join happens; the lists are never exchanged in the open.

  • 03

    Activation without third-party cookies

    PAIR is, per the v1.1 spec, “a standard for activating a common audience between two parties — namely an advertiser and a publisher”: offline matching in a clean room, then online activation with encrypted publisher IDs carried in the OpenRTB 2.6 eids object.

  • 04

    Attribution between two parties

    ADMaP v1.0 — the Attribution Data Matching Protocol, finalized February 25, 2025 — standardizes privacy-centric attribution and conversion measurement between advertisers and publishers, using private set intersection and trusted execution environments on deterministic first-party data.

  • 05

    A common vocabulary

    The Data Clean Room Guidance and Recommended Practices v1.0 establishes common DCR principles, functions, and privacy-enhancing technologies, plus limitations and guardrails — so two parties can negotiate a deployment in shared terms instead of vendor dialects.

  • 06

    Cross-vendor interoperability

    PAIR v1.1 names three deployment models — a single clean room, a single clean room with a TEE, and two interoperating clean rooms — and calls commutative cryptography particularly powerful for interoperating between clean rooms owned by different administrative parties.

The honest no

What a clean room does not solve by itself.

Eight things the room does not do for you. None of them is a reason not to deploy one — every one of them is a reason not to stop at deploying one. Nothing in this stack is privacy-protective by default; it is privacy-protective by configuration, contract, and habit.

  • 01

    Output policy

    The room constrains the computation, not your choices. What may leave, at what aggregation, with what noise, to which destinations — those are decisions the deploying parties make and enforce. No standard on this page makes them for you.

  • 02

    Legal basis and consent

    A clean room is not a consent mechanism. The permissions attached to the underlying data still govern every output, and the official guidance explicitly stops short of legal advice. Validate obligations per market — infrastructure is not a legal basis.

  • 03

    Purpose limitation

    Purpose-limited collaboration is the portfolio’s stated goal, but the limiting is done by contract and configuration. The guidance outlines guardrails; your deployment either enforces a declared purpose per output or it does not.

  • 04

    Data quality and bias

    Matching bad data privately produces private bad data. Stale CRM records, duplicate keys, and skewed coverage pass through every PET intact — match rates and readouts inherit the hygiene of the lists behind them.

  • 05

    Re-identification in outputs

    Small cells, rare combinations, and differencing across repeated or overlapping queries can re-identify individuals from outputs that each looked safe alone. Thresholds and rate limits are policy work the room does not do by itself.

  • 06

    Key compromise and collusion

    PAIR does not claim to eliminate privacy risk — the spec itself documents leaked-key, clean-room-compromise, single-bad-actor, and collusion scenarios, with required guardrails. Treat those scenarios as deployment requirements, not appendix reading.

  • 07

    Coverage and match honesty

    A matched audience is the overlap of matchable keys, not a census of shared customers. Coverage gaps, identifier churn, and formatting differences all deflate or distort match rates — report them as diagnostics with caveats, not trophies.

  • 08

    Interoperability by default

    The standards exist — PAIR for activation, ADMaP for attribution — but adoption is per-partner. Public documentation describes prerequisites for DSPs, SSPs, and publishers, not universal adoption. Validate current support with every partner in the chain.

The interoperability lane

PAIR and clean room interoperability.

Interoperability is the part of the clean-room story that has actually been standardized. PAIR v1.1 — finalized July 2025 — is the activation protocol; ADMaP v1.0 — finalized February 25, 2025 — is the attribution companion; and OPJA, IAB Tech Lab’s first clean-room interoperability standard, is deprecated and no longer supported. One hedge belongs in every plan: public documentation describes participant prerequisites and goals of enabling adoption, not universal adoption — where supported, validate current PAIR support with every clean room, DSP, SSP, and publisher in the chain before depending on it.

  • Provenance

    Donated, then opened

    PAIR — Publisher Advertiser Identity Reconciliation — was originally developed by the Google Ads team. Official wording: “Google initially donated the PAIR protocol to IAB Tech Lab, and the working group has further developed it into an open standard.” The Rearc Addressability Working Group maintains the open industry version; Google does not run it, and the older Google-developed pair Prebid module is explicitly slated for transition to the new Open PAIR module.

  • Mechanics

    Match offline, activate online

    Two phases. Offline: first-party join keys are multiple-encrypted with commutative ciphers and matched inside a clean room — or across two interoperating clean rooms — without decryption to cleartext. Online: encrypted publisher PAIR IDs ride the eids object of OpenRTB 2.6 bid requests, and DSPs that meet the spec’s prerequisites recognize and bid on the matched audience.

  • Status

    Where it stands

    The industry v1.0 went to public comment September 25 – October 25, 2024 and was finalized in early 2025 (final PDF posted February 2025). PAIR v1.1 was finalized in July 2025: per Tech Lab, it clarified protocol definitions and improved Prebid integration via the new Open PAIR module (openPairIdSystem.js). ADMaP v1.0 — finalized February 25, 2025 — is the companion interoperability standard for attribution measurement. All are final; none is in public comment as of this validation.

PAIR, match to activation — offline commutative matching in clean rooms, online activation through OpenRTB 2.6 eids, with adoption and risk hedges where the spec puts them. PAIR — MATCH TO ACTIVATION the match happens offline — activation still clears the programmatic rails Offline, in the clean room or rooms — PAIR v1.1 describes three deployment models: a single data clean room, a single clean room with a trusted execution environment, and two data clean rooms interoperating. The matching phase runs offline, before any bid is requested. OFFLINE — IN THE CLEAN ROOM(S) one DCR · DCR + TEE · two interoperating DCRs Donated, then opened — official wording: Google initially donated the PAIR protocol to IAB Tech Lab, and the working group has further developed it into an open standard. The industry v1.0 went to public comment September 25 to October 25, 2024 and was finalized in early 2025; v1.1 was finalized in July 2025, clarifying definitions and adding the Open PAIR Prebid module. Google does not run the open industry version — Tech Lab’s Rearc Addressability Working Group maintains it. DONATED, THEN OPENED donated by Google · maintained by IAB Tech Lab The advertiser’s first-party identifiers — hashed and encrypted with the advertiser’s key before matching. PAIR is, per the v1.1 spec, a standard for activating a common audience between two parties — namely an advertiser and a publisher. ADVERTISER LIST first-party join keys The publisher’s first-party identifiers — hashed and encrypted with the publisher’s key. Neither side hands the other a raw list; the match runs on multiple-encrypted keys. PUBLISHER LIST first-party join keys Commutative encryption — jane@email.com × Ka × Kp equals jane@email.com × Kp × Ka, so keys encrypted by both parties in either order match without decryption back to cleartext. PAIR v1.1 names three deployment models: a single clean room, a single clean room with a TEE, or two interoperating clean rooms. ENCRYPT + MATCH commutative ciphers The matched audience — the overlap of the two lists, held as encrypted identifiers. The v1.1 spec calls commutative cryptography particularly powerful as a means to interoperate between clean rooms owned by different administrative parties. MATCHED SEGMENT no cleartext exposed Deal and audience setup — the matched segment becomes a targetable audience under agreed deal terms. The spec lists prerequisites for DSPs, SSPs, and publishers; meeting them is a per-partner capability check, not an assumption. DEAL / SETUP publisher + DSP terms Online activation — encrypted publisher PAIR IDs are carried in the eids object of the OpenRTB 2.6 bid request. The offline match meets the standard programmatic rails here. BID REQUEST eids — OpenRTB 2.6 The DSP recognizes the encrypted IDs it received through the clean-room flow and bids for the matched audience. PAIR v1.1 added the Open PAIR module for Prebid.js (openPairIdSystem.js); users of the older Google-developed pair module must plan to transition. DSP MATCH + BID encrypted ID lookup The readout — campaign reporting on the matched audience, aggregate by design. For attribution measurement between the same two parties, ADMaP v1.0 (finalized February 25, 2025) is the companion clean-room interoperability standard. READOUT aggregate, not rows Adoption is per-partner — official sources state goals of enabling adoption and list prerequisites for DSPs, SSPs, and publishers; they do not claim universal adoption. Where supported, validate current PAIR support with every clean room, DSP, SSP, and publisher in the chain before depending on it. ADOPTION IS PER-PARTNER public docs describe prerequisites and goals — validate current support across the chain Risks are documented — PAIR does not eliminate privacy risk, and the spec says so: it documents leaked-key, clean-room-compromise, single-bad-actor, and collusion scenarios, with required guardrails. Treat those guardrails as deployment requirements, not appendix reading. RISKS ARE DOCUMENTED the spec maps leaked-key, compromise, and collusion scenarios — guardrails are required
The PAIR flow: offline commutative matching inside one or two clean rooms, then online activation through encrypted IDs in the OpenRTB 2.6 eids object — with adoption and risk hedges where the spec puts them.

OPJA, for the record

Open Private Join and Activation was IAB Tech Lab’s first clean-room interoperability standard. The official PAIR page is unambiguous: “This protocol will replace the Open Private Join and Activation (OPJA) specification, as both specifications solve the same problem. Going forward PAIR will be the designated standard.” OPJA is deprecated and no longer supported — if a vendor pitch still leans on it, that is a currency check failed.

The machinery

PETs, in plain language.

Privacy-enhancing technologies are the machinery that makes collaboration constraints enforceable. One naming precision first: there is no single IAB Tech Lab document titled “PETs Guidance.” The published guidance is the Differential Privacy Guidance (public comment November 15 – December 14, 2023; final PDF posted May 2024) plus the PETs initiative materials covering secure multi-party computation, differential privacy, and on-device analytics — with PAIR and ADMaP as the PETs-based protocol deliverables. Each technique below helps with something specific, and none of them solves the part that is a decision.

PETWhat it helps withWhat it does not solve
Private set intersection (PSI)Computes the overlap of two datasets without either side revealing its non-matching records. Named in ADMaP v1.0 as a core technique for attribution matching.What you do with the overlap. PSI finds the intersection; purpose limits, thresholds, and destinations for that intersection are output policy.
Differential privacyAdds calibrated noise so outputs resist isolating any individual. IAB Tech Lab’s Differential Privacy Guidance (final PDF posted May 2024) covers ad-tech use cases and privacy-utility tradeoffs.Parameter choices. Epsilon budgets, query limits, and drift across repeated queries still need governance — noise with no policy is just lower-quality data.
Aggregation and thresholdsReports in groups rather than rows, with minimum cell sizes — the default safe shape for clean-room outputs.Re-identification through small or overlapping cells. The threshold number is a policy decision, and differencing across queries can undo naive aggregation.
Encryption and hashingProtects data in transit and at rest and pseudonymizes join keys. PAIR’s commutative encryption is the working example: matching without decryption to cleartext.Anonymity. Hashing is pseudonymization, not anonymization — and the PAIR spec itself documents leaked-key scenarios with required guardrails.
Trusted execution environments (TEEs)Hardware-isolated computation. ADMaP names TEEs among its techniques, and PAIR v1.1 includes a single-DCR-with-TEE deployment model.Trust itself. The trust moves to the hardware vendor and attestation chain — and a TEE governs where computation runs, not what outputs may leave.
Synthetic dataStand-in datasets for development, testing, and sharing without exposing real records.The fidelity-privacy tradeoff. Statistical properties of real people can leak into synthetic sets, and no dedicated IAB Tech Lab standard covers it — treat methodology claims as vendor claims to validate.

The pattern

Read down the right-hand column: every gap is the same gap. Techniques enforce decisions — thresholds, purposes, destinations, budgets — and the decisions are output policy. That is the next section.

The door

Output policy: the part no standard writes for you.

Every clean-room deployment reduces to one question: what is allowed to leave? The guidance outlines guardrails, the protocols constrain the mechanics, and the PETs enforce whatever you configure — but the configuration is yours. Nine categories of output ask to leave a working deployment, and a twelve-point policy decides, per category, who can ask, what leaves, how small, how noisy, where it goes, how often, and whether anyone can prove it afterward.

  • 01

    Aggregate reports

    Grouped counts, reach, frequency, and composition readouts. The default output shape — still subject to minimum cell sizes and differencing protection before it ships.

  • 02

    Audience segments and activation lists

    Matched audiences leaving the room for targeting — for example PAIR’s encrypted IDs in the OpenRTB 2.6 eids object. The most useful output and the one that most needs purpose, destination, refresh, and expiry rules.

  • 03

    Match-rate and overlap statistics

    How much two datasets intersect. Operationally necessary, quietly risky: repeated overlap queries against shifting lists are a classic differencing path to individuals.

  • 04

    Attribution and conversion readouts

    Exposure-to-outcome measurement — standardized between two parties by ADMaP v1.0. Aggregate by design; the output gate keeps it that way.

  • 05

    Model features and training data

    Derived signals exported to train models elsewhere. Once out, the room’s controls no longer apply — policy must decide what a model may memorize and where it may run.

  • 06

    Lookalike seeds

    Matched audiences used to expand to similar users outside the room. The expansion happens beyond the room’s controls, so the seed’s purpose limits must travel with it.

  • 07

    Derived scores and propensities

    Per-entity values computed on joined data. A score attached to an identifier is row-level data wearing a costume — gate it like one.

  • 08

    Row-level extracts and exceptions

    The outputs that should almost never leave, and the reason the gate exists. If an exception path exists at all, it needs named approvers, logging, and an incident plan.

  • 09

    Ad-hoc query results

    The long tail of analyst — and increasingly agent — questions. Every one is an output event: scoped, thresholded, rate-limited, and logged.

The output policy gate — nine kinds of output ask to leave the room; the gate decides who can ask, what leaves, how small, how noisy, where it goes, how often, and whether it is logged. OUTPUT POLICY — WHAT LEAVES THE ROOM Inside the room — joined first-party data under the room’s controls. The room constrains the computation; it does not decide what you choose to let out. Every chip below is a candidate output that must face the gate. INSIDE THE ROOM — CANDIDATE OUTPUTS Aggregate reports — the default clean-room output shape: grouped counts and metrics. Still gated: minimum cell sizes and differencing protection decide whether an aggregate is actually safe to ship. aggregates Audience segments and activation lists — matched audiences leaving the room for targeting, e.g. via PAIR’s encrypted IDs in the OpenRTB 2.6 eids object. The most operationally useful output, and the one that most needs purpose, destination, refresh, and expiry rules. audience segments Match-rate and overlap statistics — how much of two datasets intersect. Small overlaps and repeated queries against shifting lists are a classic re-identification path; rate limits and logging apply. match rates Attribution and conversion readouts — exposure-to-outcome measurement, standardized between parties by ADMaP v1.0 (finalized February 25, 2025) using PSI and TEEs. Aggregate by design; the gate keeps it that way. attribution results Model features and training data — derived signals leaving the room to train models elsewhere. Once exported, the room’s controls no longer apply; the output policy must decide what a model may memorize and where it may run. model features Lookalike seeds — matched audiences used to expand to similar users outside the room. The expansion happens beyond the room’s controls, so the seed’s purpose limits must travel with it. lookalike seeds Derived scores and propensities — per-entity values computed on joined data. A score attached to an identifier is row-level data wearing a costume; gate it like one. derived scores Row-level extracts and exceptions — the outputs that should almost never leave, and the reason the gate exists. If an exception path exists, it needs named approvers, logging, and an incident plan. row-level slices Ad-hoc query results — the long tail of analyst (and increasingly agent) questions. Each one is an output event: scoped, thresholded, rate-limited, and logged, or it is a leak waiting for a query planner. ad-hoc queries The output policy gate — the questions every output answers before it ships: who can ask (named roles), what leaves (enumerated output types), how small (aggregation thresholds), how noisy (differential-privacy parameters where used), where it goes (destination allow-lists), how often (rate limits against differencing), and logged (every output event recorded against a policy version). These are decisions; the PETs enforce them. OUTPUT POLICY GATE who can ask · what leaves · how small · how noisy · where it goes · how often · logged What clears the gate — outputs that are aggregate, above threshold, noised where the policy defines it, bound to a declared purpose and an allow-listed destination, and logged against the policy version that approved them. This is the product of a clean-room deployment. CLEARS THE GATE aggregate · thresholded · noise where defined purpose-bound · destination-bound · logged What stops at the gate — row-level extracts, re-identifiable slices (small cells, rare combinations, differencing across repeated queries), reuse beyond the declared purpose, and unlogged destinations. If these can pass, the room’s other controls are decoration. STOPS AT THE GATE row-level extracts · re-identifiable slices off-purpose reuse · unlogged destinations a clean room without output policy is just a safer room with an unsafe door
The output policy gate: nine candidate outputs inside the room, one gate deciding who can ask, what leaves, how small, how noisy, where it goes, how often, and logged — and two destinies below it.

The twelve-point output policy checklist.

  • Enumerate every output type the deployment can produce — if it can be queried, it is an output.
  • Set minimum aggregation thresholds per output type, and document who set them and why.
  • Define noise and differential-privacy parameters where used — and what happens when a query exceeds its budget.
  • Restrict who can run queries and trigger exports — named roles, not shared logins, for humans and agents alike.
  • Allow-list destinations: where each output type may land, and which systems may consume it.
  • Bind every output to a declared purpose — including measurement-only outputs that must never feed optimization.
  • Propagate consent and permission signals into outputs: a restriction on the input row survives into everything derived from it.
  • Test outputs for re-identification — small cells, rare combinations, and differencing across repeated or overlapping queries.
  • Rate-limit and review repeated queries: drift across near-identical queries can reconstruct what one query cannot.
  • Log every output event — who asked, what left, where it went, under which policy version.
  • Set retention and deletion rules for outputs and derived artifacts — segments and models outlive the room that made them.
  • Put the policy in the contract: enforcement, audit rights, and an incident path for outputs that should not have shipped.

Policy beats technique

Aggregation thresholds, noise parameters, purpose limits, and destinations are decisions. The PETs make those decisions enforceable; they do not make them for you. A clean room without output policy is just a safer room with an unsafe door.

Agents at the door

Agentic implications.

Clean rooms were designed for a world where a human analyst runs a query, reads the result, and moves on. Agentic workflows change the tempo, not the rules: the same output policy now has to hold against systems that query continuously, chain results automatically, and activate what they find. Six implications follow — all of them arguments for making the policy machine-enforceable before the first agent connects.

  • 01

    Agents are query engines

    An agent wired to a clean room can run more queries in an afternoon than your analysts ran last quarter. Repeated-query and differencing protections stop being theoretical the day the first query loop ships.

  • 02

    Policy must be machine-readable

    An output policy that lives in a PDF does not bind an agent. Allow-lists, thresholds, purposes, and rate limits have to exist as enforced configuration — the gate the agent actually hits, not the intention it never reads.

  • 03

    Activation needs provenance

    When an agent buys against a PAIR-matched segment, it should be able to answer: which collaboration produced this, under what purpose, refreshed when, expiring when. A segment without provenance is a liability moving at machine speed.

  • 04

    Interop standards are agent affordances

    Standardized carriage — encrypted IDs in OpenRTB 2.6 eids, the Open PAIR Prebid module — is what makes clean-room outputs legible to buying agents at all, where supported. Bespoke integrations are where agentic workflows go to break.

  • 05

    Measurement-only means measurement-only

    Outputs cleared for measurement must not silently feed optimization loops. An agent that closes that loop without authorization has converted a permitted use into a prohibited one — automatically and at scale.

  • 06

    Audit is the agent’s alibi

    Logged output events — who asked, what left, where it went, under which policy version — are how you prove an autonomous workflow stayed inside policy. No log, no defense.

Implementation lens

Implementation lens.

The same standards land differently depending on where you sit in the chain. Select your company type for the version of this page that applies to you.

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What to demand

Write outputs into the contract before the first query: enumerated output types, thresholds, purposes, destinations, logs, audit rights. Ask which standards each vendor and partner actually implements — DCR Guidance alignment, PAIR, ADMaP — and validate current support per partner. Treat match rates as diagnostics with caveats, not success metrics.

  • DCR Guidance v1.0
  • PAIR v1.1
  • Output policy checklist
  • Consent propagation
What to operationalize

Maintain a capability matrix per clean room and per partner: PAIR support, ADMaP support, threshold defaults, query review, export logging. Price the policy work into every data collaboration scope — the room is the cheap part; the governance is the engagement.

  • Partner capability matrix
  • PAIR prerequisites
  • ADMaP v1.0
  • Query governance
What to implement

Your first-party audience is the asset; clean-room standards are how it gets monetized without being handed over. Implement PAIR matching where supported, carry encrypted IDs in OpenRTB 2.6 eids, plan the move to the Open PAIR Prebid module — and let output policy protect the audience IP, not just the users in it.

  • PAIR v1.1
  • OpenRTB 2.6 eids
  • Open PAIR Prebid module
  • Audience IP protection
What to align

Clean rooms are the collaboration backbone behind retail media measurement — overlap, attribution, and closed-loop readouts all flow through them. Gate commerce outputs like any other: a new-to-brand readout is still an output, and a row-level basket extract is still a row-level extract.

  • Aggregate readouts
  • Attribution via ADMaP
  • Purpose limits
  • Output gate
What to engineer

Implement the interoperability protocols — PAIR including the two-DCR model, ADMaP for attribution — and expose policy as configuration: thresholds, noise parameters, destination allow-lists, rate limits, and logs that customers can audit. Methodology transparency is a sales asset; “trust us” is not an architecture.

  • Two-DCR interoperability
  • TEE deployment model
  • Policy-as-configuration
  • Audit logging
What to engineer

Meet the PAIR prerequisites the spec assigns to your role: encrypted ID handling, eids carriage, and matched-audience bidding. Plan the transition from the older Google-developed pair Prebid module to Open PAIR (openPairIdSystem.js), and respect measurement-only boundaries on any clean-room-derived signal.

  • PAIR DSP/SSP prerequisites
  • eids handling
  • openPairIdSystem.js
  • Measurement-only boundaries
What to cover

ADMaP v1.0 is the standard lane for two-party attribution — build to it where supported. Document differential-privacy parameters and methodology, test your own outputs for re-identification, and resist the row-level exception requests that arrive the week after launch.

  • ADMaP v1.0
  • Differential Privacy Guidance
  • Methodology disclosure
  • Re-identification testing
What to govern

The room is not a legal basis and the guidance is not legal advice — your consent obligations attach to the data, not the infrastructure. Carry permissions from inputs into outputs, put the twelve-point checklist into contracts, define the incident path, and validate obligations per market.

  • Output policy contract
  • Consent propagation
  • Retention & deletion
  • Audit rights
No Fluff POV

No Fluff POV.

Clean rooms earned their place: matching without cleartext, analysis without data movement, and — finally — real interoperability standards instead of vendor dialects. But the vendor pitch stops at the walls, and the walls were never the hard part. The hard part is the door. The standards now cover the room (DCR Guidance v1.0), activation out of it (PAIR v1.1), and attribution through it (ADMaP v1.0); none of them sets your thresholds, names your destinations, or logs your exports. Teams that treat the room as the deliverable buy a venue; teams that treat the output policy as the deliverable ship a product.

  • Output policy is the product. The room is the venue; what leaves it is what you actually shipped.
  • Name the standards precisely: DCR Guidance v1.0, PAIR v1.1 (finalized July 2025), ADMaP v1.0 (finalized February 25, 2025) — and OPJA as deprecated, superseded by PAIR.
  • Treat PETs as enforcement, not absolution: PSI, differential privacy, TEEs, aggregation, and encryption enforce decisions someone still has to make.
  • Hedge adoption honestly: public documentation describes prerequisites and goals, not universal adoption — validate current support with every partner in the chain.
  • Carry permissions through: consent and purpose restrictions on inputs survive into outputs — an output that forgets its permissions is a leak with better paperwork.
  • Put the twelve-point checklist in the contract before the first query — thresholds, destinations, logging, audit rights, and an incident path for outputs that should not have shipped.

The point

A clean room without output policy is just a safer room with an unsafe door.

Validate, don’t assume

Primary sources to validate.

Standards, guidance, and implementation references last validated: June 2026. Specifications, public-comment status, frameworks, APIs, and implementation guidance change. Validate against official documentation before implementation.

Primary sources to validate 9 sources
  • IAB Tech Lab · checked 2026-06-13 · Primary

    Canonical Tech Lab DCR standards hub (last updated July 22, 2025), produced by the Rearc Addressability Working Group. States: 'In July 2024, we released the Version 1.0 of Data Clean Room Guidance'; 'PAIR version 1.1 was finalized in July 2025'; ADMaP 1.0 finalized February 2025. Carries the official OPJA deprecation wording: OPJA 'has since been superseded by the donation of PAIR to Tech Lab by Google... OPJA if therefore a deprecated standard and no longer supported' (typo 'if' for 'is' is in the original). No DCR Guidance v2.0 exists. Supports: DCR portfolio overview (Guidance + PAIR + ADMaP), Official OPJA deprecation wording, Current versions/statuses.

  • IAB Tech Lab · checked 2026-06-13 · Primary

    The Version 1.0 guidance document, linked from the DCR hub. Establishes common DCR principles, functions, and privacy-enhancing technologies, plus limitations and guardrails for engaging with DCRs. DATE CAUTION: the site's history is internally inconsistent (public comment opened Feb 2023; the PDF lives under a 2023/06 upload path while the hub says v1.0 was released July 2024) — quote the hub page's own 'July 2024' statement rather than asserting a definitive finalization date. Supports: Citing the DCR Guidance document, Principles/functions/PETs covered by the guidance.

  • IAB Tech Lab · checked 2026-06-13 · Primary

    Official PAIR page. Current version 1.1 (finalized July 2025); v1.0 finalized early 2025. PAIR was originally developed by the Google Ads team and donated to Tech Lab; it uses commutative cryptography to match encrypted first-party identifiers without cleartext exposure. Carries the supersession wording: 'This protocol will replace the Open Private Join and Activation (OPJA) specification, as both specifications solve the same problem. Going forward PAIR will be the designated standard.' v1.1 refines definitions and improves prebid integration via a new Open PAIR module. Do not overclaim adoption — official sources state goals and participant prerequisites, not adoption counts. Supports: PAIR current version and status, OPJA supersession wording, What PAIR standardizes.

  • IAB Tech Lab (Rearc Addressability Working Group) · checked 2026-06-13 · Primary

    The v1.1 spec (© 2025, 38 pp). Verbatim: PAIR was 'originally developed by Google Ads team' and 'is a standard for activating a common audience between two parties — namely an advertiser and a publisher.' Covers commutative ciphers, offline DCR matching plus online OpenRTB activation via the eids object (OpenRTB 2.6), and three deployment models — Single DCR; Single DCR with TEE; 'Two Data Clean Rooms (PAIR interoperability)' — plus the Open PAIR Prebid.js module (openPairIdSystem.js; users of the older Google-developed pair module 'must plan to transition'). The spec itself documents leaked-key, DCR-compromise, and collusion scenarios with required guardrails — do not claim PAIR eliminates all privacy risk. Supports: PAIR mechanics and deployment models, Cross-DCR interoperability, Open PAIR prebid module, Google-origin attribution.

  • IAB Tech Lab · checked 2026-06-13 · Primary

    September 25, 2024 release announcing the industry version of PAIR for public comment (until October 25, 2024). Verbatim: 'Google initially donated the PAIR protocol to IAB Tech Lab, and the working group has further developed it into an open standard'; PAIR 'provides a privacy-centric approach for advertisers and publishers to match and activate their first-party audiences for advertising use cases without relying on third-party cookies.' Google donated PAIR — do not say Google still owns or runs the industry version. Supports: Google donation of PAIR, v1.0 public-comment dates (Sept 25–Oct 25, 2024).

  • IAB Tech Lab · checked 2026-06-13 · Primary

    Official OPJA page carrying the deprecation notice, verbatim: 'On the close of the public comment period (October 25, 2024) and the release of the final version of PAIR v1.0, IAB Tech Lab will cease to support OPJA.' OPJA was Tech Lab's first DCR interoperability standard (public comment opened Feb 16, 2023 alongside the DCR Guidance; finalized as v1.0) before PAIR superseded it. OPJA is deprecated and unsupported — never describe it as current or merely 'on hold'. Supports: Official OPJA deprecation/supersession wording, What OPJA was (historical).

  • IAB Tech Lab · checked 2026-06-13 · Primary

    ADMaP v1.0 — a DCR interoperability standard for privacy-safe attribution/conversion measurement between advertisers and publishers using PETs (private set intersection, trusted execution environments) on deterministic first-party data. Verbatim status: 'ADMap was open for public comment until November 14, 2024 and finalized on February 25, 2025.' Developed by the Rearc Addressability and PETs Working Group. Use this page's expansion 'Attribution Data Matching Protocol' — other Tech Lab pages render the name inconsistently. Supports: Measurement-side DCR interoperability standard, ADMaP version/status.

  • IAB Tech Lab · checked 2026-06-13 · Supporting

    PETs initiative/working-group page: develops standards, open-source software, and guidance for integrating PETs into ad tech — secure multi-party computation, differential privacy, on-device analytics — and names ADMaP and PAIR as PETs-based deliverables. NAMING CAUTION: no standalone Tech Lab document literally titled 'PETs Guidance' exists; the published PETs guidance is the Differential Privacy Guidance plus this initiative's materials. Supports: Scope of official PETs work, Linking PAIR/ADMaP to the PETs program.

  • IAB Tech Lab · checked 2026-06-13 · Primary

    The PETs Working Group's Differential Privacy Guidance — the concrete published PETs guidance document. Public comment Nov 15–Dec 14, 2023; final PDF posted May 2024 (page 'Last updated: May 09, 2024'). Covers the definition of differential privacy, ad-tech use cases, privacy-utility tradeoffs, and where differential privacy is or is not suitable. Supports: Official PETs guidance document (final), Differential privacy in ad measurement.

Platform capabilities and naming change quickly. Last validated: June 13, 2026. Check current documentation before implementation.Standards, guidance, and implementation references last validated: June 2026. Specifications, public-comment status, frameworks, APIs, and implementation guidance change. Validate against official documentation before implementation.

Next step

Standing up clean-room collaboration, PAIR activation, or output governance?

The operating work is to wire output policy — thresholds, purposes, destinations, logs, audit rights — into the collaboration path before agents start querying it at machine speed.