[Change] § 5.6 — Give cost_method an extensible vocabulary, and say what several pricing[] entries mean #94

What kind of change?

Change a field's type or shape

Which section?

5.6 — Commercial terms

Current text

| `pricing[]` | Array[Object] | mixed | See below |
| `pricing[].cost_method` | Enum | seller-set | CPM, CPC, flat, etc. |

Proposed text

§ 5.6, replace the cost_method row with:

| `pricing[].pricing_id` | String | immutable | Names the entry. Never reused for another `cost_method`, `cost_parameters`, `currency`, or `transaction_mechanisms[]` |
| `pricing[].cost_method` | String | seller-set | The billable unit: a core term (Cost methods, below), or an extension term `<domain>:<name>` |
| `pricing[].rate_per` | Number | seller-set | REQUIRED for an extension term. Units per rate: `1` or `1000` |
| `pricing[].unit` | String | seller-set | REQUIRED for an extension term. A short label for one unit, such as `engagement` |
| `pricing[].cost_definition` | String (URL) | seller-set | REQUIRED for an extension term. Public definition of one unit and the `cost_parameters` keys, on the term's prefix domain or a subdomain |
| `pricing[].cost_parameters` | Object | seller-set | The keys the term requires |
| `pricing[].transaction_mechanisms[]` | Array[Enum] | seller-set | OPTIONAL. Mechanisms this entry prices. Absent: all offered |

After the table:

`pricing[]` entries are alternatives. The buyer commits under exactly
one, named by `commitment.pricing_id`; it MUST cover the selected
mechanism. Only that entry enters `agreed_rate`, `derived_units`, and the
`floor` comparison. Two entries MUST NOT share `cost_method`,
`cost_parameters`, `currency`, and a mechanism.

A line item MAY offer entries in several currencies. A commitment is in
exactly one: the committed entry's `currency`. `commitment.currency`, when
present, MUST equal it, and `min_spend`, the `commitment_bounds` budgets,
and § 3.1 `delta_flat` are read in it. OpenProposal never converts.

§ 5.6.1, add: `pricing_id`, REQUIRED when `pricing[]` has more than one entry.

After § 5.6.2, add an unnumbered subsection:

#### Cost methods

An IAB-maintained vocabulary, versioned apart from the schema; adding a
term needs no schema change. Bare names belong to it and compare
case-insensitively, so `flat` is `FLAT`:

| `cost_method` | One unit | Rate per | `cost_parameters` |
| :--- | :--- | :--- | :--- |
| `CPM` | impression | 1,000 | |
| `CPMV` | viewable impression | 1,000 | `viewability_standard` |
| `CPC` | click | 1 | |
| `CPCV` | completed view | 1 | |
| `CPV` | view | 1 | `view_threshold` |
| `CPP` | rating point | 1 | `demographic`, `rating_source` |
| `CPA` | action | 1 | `event`, `attribution_window`, `event_source` |
| `PLAY` | DOOH play on one screen or one sync group | 1,000 | |
| `TIME` | `time_unit` | 1 | `time_unit`: `hour` \| `day` \| `week` |
| `FLAT` | line item | | |

Anyone MAY define an extension term. Its prefix is a domain the definer
controls, such as `example-ssp.com:cpa_guaranteed`; a seller's own terms
MUST use its `seller_domain`. The `cost_definition` URL's host MUST be
the prefix domain or a subdomain of it. A term's meaning MUST NOT change once
published; a changed meaning takes a new name.

When `basis` is `spend`, `amount` is the seller total, on the same
terms as `agreed_rate`, including selected `delta_flat` charges
(§ 3.1), which MUST NOT exceed it. `FLAT` commits on `spend`.
For other entries, `derived_units` = (`amount` − those charges) ÷
`agreed_rate` × rate per, rounded down to a whole unit; `TIME` units are `time_unit`s from
`flight_start` through `flight_end`, inclusive. When `basis` is `units`, the seller total is `amount` ÷ rate
per × `agreed_rate` plus those charges; `min_spend` and
`commitment_bounds` budgets apply to it. A seller fee is never a
`pricing[]` entry. A consumer MUST treat an entry with an unrecognized
`cost_method`, or an extension entry that breaks these rules, as
unavailable, not the line item as invalid.

§ 3.1: `delta_cpm` adjusts only `CPM` and `CPMV` entries; an option
priced only by `delta_cpm` MUST NOT resolve against any other entry.

Why

We ask two separable things: a vocabulary for cost_method, and a meaning for several pricing[] entries. Either can be adopted alone.

cost_method is the billable unit, with no list and no meaning. § 5.6 ends the Enum with "etc.", and § 5.6.1 derives units from it by an unstated divisor. Views, rating points, and actions also need counting parameters.

A closed core list alone fails: a new model, such as the outcome-based pricing #80 asks for, waits for registration, and a proprietary one never gets in. Sellers write flat plus prose instead, as #45 does. Free strings fail the other way: CPCV and cost_per_completed_view never match.

A domain prefix can't collide, and it names who answers for the term, as <seller_namespace> does in § 2.2. With cost_definition on that domain, a reader checks a term's definer as it checks a seller (#61). Inline rate_per and unit keep the record self-contained. CPM, CPMV, CPC, daily TIME, and FLAT map to OpenDirect 2.1 ratetype; Ad Manager cost types add CPCV.

Nothing says what two pricing[] entries mean: a choice, a per-currency copy, or charges that add up. The comment template names the gap: "pricing[] sits above transaction_mechanism." A § 3.1 delta on transaction_mechanism changes only the rate, not the floor or unit. We ask: alternatives with an id, chosen once in commitment, which takes that entry's currency.

A spend amount includes selected delta_flat fees, as @aleksUIX's fee-basis PR (#117) proposes, and derived_units counts only the rest. Otherwise a fee overruns amount or goes unpaid.

Details: Pricing models and price alternatives: full rationale and examples

Knock-on effects

• § 2.1: the summary lists each entry's pricing_id, cost_method, gross_rate, and currency.
• Our reply on #30 locates an entry by cost_method; pricing_id replaces that. #63's record carries commitment.pricing_id.
• commitment_bounds impressions count the committed entry's units; min_spend and the commitment_bounds budgets apply to the seller total, selected delta_flat charges included.
• @dineshbhat's commitment.amount change request (#115) makes a seller fee its own pricing[] entry. Entries here are alternatives, so a fee there would be another choice, not a charge.
• Whether agreed_rate is gross or net of agency commission stays open in our floor and rate-basis reply on #30, open question 3, and tax in the billing.tax_inclusive flag that #115 proposes. amount uses the same terms as agreed_rate, so the rule holds either way.
• § 1.1 carriers take five OpenDirect rate types and deals take CPM; the controlling counter bills other terms.
• #82 asks what a DOOH CPM counts; our DOOH plays filing answers it with impression_multiplier.
• Breaking: commitment.pricing_id is REQUIRED with several entries; delta_cpm options, § 5.3 audiences included, resolve only against CPM and CPMV entries. flat stays valid.

Open questions for the working group

1. Entries with different cost_methods share one commitment_bounds, so should min_impressions and max_impressions count the committed entry's units, as we propose, be renamed min_units and max_units, move into each entry, or give way to budget-only bounds?
2. Should § 3.1 Selectable structure delta_cpm adjust only CPM and CPMV entries, as we propose, or read as an adjustment per rate unit on every entry?
3. Should § 5.3 Audience reach audiences accept delta_pct and delta_flat, so that audience options can price non-CPM entries, or should audience options resolve only against CPM and CPMV entries?
4. Should a programmatic guaranteed or private auction entry in a term that the § 1.1 Downstream standards deal carriers can't express, such as CPCV, be allowed and billed outside the deal carrier on the controlling count, as we propose, discouraged with a SHOULD NOT, or forbidden?
5. Should the buyer name its entry in commitment.pricing_id, as we propose, or should pricing become a § 3.1 Selectable structure selectable field that the buyer sets through the selected[] key proposed in the buyer's selection key (#22)?

Would this break an implementation already built to this draft?

Yes — breaking

Alternatives you considered and rejected

• A closed registry, as #62 uses for schemes. The closed list's delay; we keep its unknown-token rule.
• AdCOM 1.0's "vendor-specific codes typically starting at 500". Two vendors can pick the same code.
• Prefix core terms too (iab:CPM). Breaks every example.
• One price per line item. Duplicate line items over one inventory; § 2 subsetting lets a buyer commit both.
• Revenue share. A commission on attributed sales, not a rate on a unit (gist).

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Revised 2026-10-27: A PLAY unit is one play on a screen or sync group, following @premesh, and derived_units rounds down to a whole unit, following @EvgenyAndroid.

Analyzed and generated with the help of Claude, fully reviewed by me.