IAB Tech Lab on October 23, 2026 extended the public comment period for AAMP 3.0 and its core specification, OpenProposal, to Tuesday, November 10, 2026. The draft, which defines how buying and selling software agents exchange advertising proposals, was due to close for comment on October 22. The new date adds 19 days, turning a 30-day window that opened on September 22 into one of 49 days, by PPC Land's count.

In Short

The ad industry's technical standards group wrote a draft rulebook for how AI programs that buy and sell ads should describe a deal to each other, and asked the public to comment by October 22. So many people responded that the group gave everyone until November 10 instead. Anyone building or using AI ad-buying tools now has nearly three more weeks to shape the rules before they are revised.

What the extension says

The notice came from IAB Tech Lab's company page on LinkedIn. "Due to overwhelming demand, we're extended the Public Comment period for AAMP 3.0 and OpenProposal until Tuesday November 10, 2026," according to the post, which carried the hashtags #AgenticAdvertising, #AAMP and #OpenProposal and a shortened link to the specification's GitHub repository. The post went out under the label "BREAKING NEWS".

Anthony Katsur, chief executive officer of IAB Tech Lab, shared it on his own profile the same day. "Wow! Public comment on AAMP 3.0 and OpenProposal has been immense! Thank you. We're extending public comment until Nov 10," according to Katsur.

Neither post puts a number on the volume. How many comments arrived, from how many companies, and on which sections, is not stated. The only public trace is the repository itself, which on October 24 showed 99 open issues and 9 open pull requests, alongside 19 commits, 15 branches, seven stars and one fork. Those counts include the repository's own tracking issues, so they are an upper bound on outside comment rather than a measure of it.

Timing is notable in its own right. The extension was posted the day after the original deadline had passed. On October 24, the repository's README still listed the comment period as closing on 2026-10-22, and its process documents had not been updated to the new date. Under the comment process published in the repository, issues filed after the close are labelled post-comment and held for the following draft. Whether comments filed on October 23, before the notice appeared, count as on time is not addressed in either post.

What OpenProposal is

OpenProposal sits at the centre of AAMP 3.0, IAB Tech Lab's framework of Agentic Advertising Management Protocols. According to the repository, it is "the descriptive specification for what is being bought and sold, engineered so a buying agent can parse and evaluate it at machine speed." The object is meant to carry a deal from the first brief through to binding commercial terms, and the repository describes it as "the canonical object a seller manages alongside its OMS and ad server."

The draft is explicit about its status. "This is a draft. Nothing here is a ratified IAB Tech Lab standard. Do not build production systems against it expecting stability," according to the repository. The version announced for comment is tagged v3.0-draft-1, the main branch always holds the current draft, and every normative change is to be recorded in a changelog alongside the issue that prompted it.

PPC Land covered the draft when IAB Tech Lab released it on September 22, with its 71 fields grouped under 11 headers. The repository asks readers to grasp three design rules before reading the field tables.

No inheritance

Every line item is fully self-contained. "A field never takes its value from the parent proposal or a sibling line item," according to the repository. A buyer agent reading one line item therefore does not need to reconstruct values from elsewhere in the proposal.

Seven mutability markers

Each field carries exactly one marker: immutable, seller-set, selectable, settable, supplied, requestable or derived. "The marker is what tells a buying agent whether it can act unilaterally," according to the repository.

Constraint satisfaction, not negotiation

The third rule is the one IAB Tech Lab most wants tested. "Composition is constraint satisfaction, not negotiation. Of 71 fields, only 3 require a round trip with the counterparty. That ratio is the design claim the draft is asking you to test," according to the repository. Put differently, about 4% of the fields require back-and-forth with the other side, by PPC Land's calculation. The rest are meant to be resolved by the buyer's software within limits the seller has already declared.

OpenProposal does not replace existing execution standards. Each line item, according to the repository, "lands in the one its transaction_mechanism maps to" - OpenDirect 2.1, the Deals API or OpenRTB 2.6. That links the proposal stage to the plumbing already used for direct buys, programmatic guaranteed deals and auctions.

The seven open questions

IAB Tech Lab published seven questions it particularly wants answered, each with its own tracking issue. Several go to the heart of the design rather than its edges.

The first asks whether per-field mutability belongs in version 3.0 at all, or whether sellers should instead publish a catalogue of whole line items. The second asks whether seller catalogues, referenced through a catalog_ref field, belong in 3.0 or whether the object should stay fully inline until a later version. The sixth asks whether payment_terms and invoicing_party, usually identical across a seller's inventory, should become catalogue references - which would sit uneasily with the no-inheritance rule.

Two questions concern coverage. The format registry has no entries for audio, connected TV or digital out-of-home, so it cannot yet describe half the channels the draft declares. And the proposed list of environments - web, app, CTV, DOOH and audio streaming - was not derived from implementation experience, according to the repository, and needs checking against real inventory.

The remaining two are about measurement and bundling. When one line item guarantees a viewable rate and another a completion rate, the draft has no normalised way to compare them. A separate question asks whether a min_line_items field is needed so a seller can require that parts of a proposal be bought together.

How comments are handled

Anyone with a GitHub account may comment. "You do not need to be an IAB Tech Lab member to comment," according to the repository. The routes are split by purpose: an issue for something unclear or missing, a change request or pull request for proposed wording, comments on the tracking issues for the open questions, an implementation feedback form for those who tried to build against the draft, and GitHub Discussions for general questions.

Commenting and deciding are separate. The working group reviews every comment and gives each a written disposition - accepted, accepted with modification, rejected with reason, or deferred - recorded in a public disposition log. Maintainers are to label new comments within five business days.

Some of the process is still blank. On October 24, the governance document left the working group's members, its chairs and its decision rule blank, and said they would be filled in during the comment period. The dates for adjudication, publication of the disposition log and the revised draft were also still to be set. Whether the revised draft goes straight to ratification or to a second comment period depends, according to the repository, on how much changes.

Machine-readable schemas are not part of this draft. "They will follow the first revision, after the comment period closes on 2026-10-22," according to the repository. With the close now moved to November 10, the schemas presumably slip by at least the same margin, though IAB Tech Lab has not said so. Until then, worked examples in YAML are the only reference for the object's shape.

The specification text is licensed under Creative Commons Attribution 3.0, and the scripts and workflow code under the Apache License 2.0. The repository lists three contributors - Siraj M, Matthew Jacobs and an account named Claude - and its code is entirely Python. Its most recent merge, about two weeks before October 24, added a label named bootcamp-2026-09-24.

Why the extension matters

For an industry that has spent 2026 arguing over which agent protocol to back, 19 extra days is not trivial. IAB Tech Lab has moved quickly this year: it named its agentic programme AAMP in February, and in July shipped AAMP 2.3 with a field meant to stop agents from inventing CPM values. OpenProposal extends that work upstream, to the request for proposal stage that agencies and publishers still largely handle by email and spreadsheet.

The proposal stage is also where IAB Tech Lab's standards meet competition most directly. In August its chief operating officer, Shailley Singh, listed 13 business functions that AAMP and the rival Ad Context Protocol both address, from media planning to pricing and deal creation. Both rely on the MCP as transport, which Singh argued does not make them complementary. A longer comment window gives companies weighing the two more time to put their objections on the record before IAB Tech Lab locks the object's shape into schemas.

Scale remains the open problem. In September, Adform's chief technology officer said neither AdCP nor AAMP runs at scale, estimating that a custom deals integration with one SSP takes 250 to 350 days of work against roughly 50 on a shared standard. That arithmetic is the case for a single proposal object - and also why the details matter. A standard that ships with a format registry unable to describe CTV or audio, or with a mutability model that sellers reject, would leave integrators building custom work around it anyway.

The earlier Deals API offers a reference point for how long the cycle can take. IAB Tech Lab released version 1.0 for comment on December 5, 2025, with comment open until January 31, 2026, and that version explicitly excluded proposals, revisions and negotiations. OpenProposal is, in part, the piece that version left out.

What the extension does not reveal is whether "immense" means a broad base of commenters or heavy engagement from a few large players. The disposition log, once published, will show which. Until then, the claim that 3 fields out of 71 are enough for two agents to agree a deal remains exactly what the repository calls it: a design claim, open to test.

Timeline

Summary

Who: IAB Tech Lab, the ad industry's nonprofit technical standards body, and its chief executive officer Anthony Katsur. The change affects buyers, sellers, agencies and companies building AI agents for media buying.

What: IAB Tech Lab extended the public comment period for AAMP 3.0 and the OpenProposal specification, a draft object model of 71 fields in which only 3 require a round trip between buyer and seller. The extension adds 19 days, from October 22 to November 10, 2026. Neither the organisation nor Katsur disclosed how many comments had arrived.

When: The extension was posted on LinkedIn on October 23, 2026, the day after the original deadline. Comment now closes on Tuesday, November 10, 2026.

Where: Comments are filed on the public IABTechLab/OpenProposal repository on GitHub, open to anyone with a GitHub account, member or not.

Why: According to IAB Tech Lab, the extension responds to "overwhelming demand". It gives more time to contest core design choices, including per-field mutability, seller catalogues and the format registry's lack of CTV, audio and DOOH entries, before the working group revises the draft and publishes machine-readable schemas.