[Change] § 5.1, § 5.9 — Say which channel a SEARCH_SOCIAL line item carries #112

What kind of change?

Change a normative requirement (MUST / SHOULD / MAY)

Which section?

Whole document / more than one section

Current text

§ 5.1: | `channel` | Enum | immutable | `display` | `video` | `audio` | `ctv` | `dooh` | `native` …
§ 5.9: | `buying_route` | Enum | seller-set | `DIRECT_PUBLISHER` | `PUBLISHER_AD_SERVER` | `SSP_PLATFORM` | `DSP` | `SEARCH_SOCIAL` |

Proposed text

§ 5.9, after the table:

`buying_route` says how a line item is bought, not what it is. A line item whose
`buying_route` is `SEARCH_SOCIAL` still carries exactly one `channel` from § 5.1,
chosen by its ad format (for example: in-feed video → `video`; a sponsored post
assembled from native assets → `native`; a static image unit → `display`).

Search text ads have no `channel` value in 3.0. A seller MUST NOT offer them
under OpenProposal 3.0.

Why

buying_route lists SEARCH_SOCIAL, but channel has no search or social value. So a seller offering a social line item can't fill channel, which is REQUIRED and immutable. A buyer agent also can't tell whether such line items are in scope. With this paragraph, the routing value is consistent with the channel definition that #90 proposes (by AdCOM ad format), and the search-text gap is stated rather than left to guesswork.

Knock-on effects

None to fields. It's one paragraph. If the working group would rather add a search channel, this draft's second paragraph flips to define it instead.

Would this break an implementation already built to this draft?

No — additive or editorial.

Filed after the 2026-10-22 close of the comment period, so we understand this is post-comment and for the next draft. Submitted by Hypermindz (buy-side agentic media planning platform).