> ## Documentation Index > Fetch the complete documentation index at: https://docs.semicola.com/llms.txt > Use this file to discover all available pages before exploring further. # Channel groups > Express composite inventory intent on a campaign, compile it into separate media buys, and report by the same grouping. A **channel group** is one coherent inventory selection inside a campaign. It combines AdCP inventory dimensions without inventing new channel values. Mobile web display, for example, is: ```json theme={null} { "channels": ["display"], "propertyTypes": ["website"], "deviceTypes": ["mobile"] } ``` It is not `channel: "mobile_web"`: `mobile_web` isn't an AdCP media channel. Semicola uses the channel group id to split and label media buys. It doesn't filter discovery by a group, check selected products against the group's definition, or turn the definition into package targeting. Check the discovery results and the seller's product details before you assign a `channelGroupId`. Within one dimension, values are alternatives (OR). Across dimensions, they combine (AND). A group with `channels: ["ctv", "olv"]` and `deviceTypes: ["ctv", "mobile"]` allows either channel and either device. For pairwise logic such as "CTV on TV devices, or online video on mobile", make two groups. ## Groups split media buys One AdCP media buy can't carry arbitrary combinations of channel, property type, device and format, so Semicola compiles a campaign by this rule: ```text theme={null} channel group × seller × settlement currency = one media buy ``` If a campaign has `mobile-web-display` and `ctv` groups, products in each become separate draft buys even with the same seller. They stay in one campaign. ## Save preset groups Pass `channelGroups` to `save_campaign`. A preset is shorthand: Semicola expands it and saves the full definition with its preset version, so a later preset change never alters an existing campaign. ```json theme={null} { "advertiserId": 12, "name": "Streaming launch", "budget": { "total": 50000, "currency": "USD" }, "channelGroups": [ { "channelGroupId": "mobile-web-display", "presetId": "mobile_web_display" }, { "channelGroupId": "ctv", "presetId": "ctv" } ], "idempotencyKey": "streaming-launch-2027-02" } ``` | Preset | Saved definition | | -------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `display` | `channels: ["display"]` | | `olv` | `channels: ["olv"]` | | `ctv` | `channels: ["ctv"]` | | `mobile_web_display` | `channels: ["display"]`, `propertyTypes: ["website"]`, `deviceTypes: ["mobile"]`, and the display `formatKinds` (`image`, `html5`, `display_tag`, `image_carousel`, `native_in_feed`, `sponsored_placement`, `responsive_creative`, `custom`) | | `mobile_web_olv` | `channels: ["olv"]`, `propertyTypes: ["website"]`, `deviceTypes: ["mobile"]` | The simple presets make no property, device or format assumption: `ctv` means the AdCP CTV channel, not only a TV set or only a CTV app. A preset group's `name` defaults to the preset's name ("Mobile web display", "CTV"…); pass `name` to change it. ## Define your own group ```json theme={null} { "channelGroupId": "premium-streaming-video", "name": "Premium streaming video", "inventory": { "channels": ["ctv", "olv"], "propertyTypes": ["ctv_app", "website"], "deviceTypes": ["ctv", "desktop"], "formatKinds": ["video_hosted", "video_vast"] } } ``` `channels` is required and takes AdCP channel values only; put an alias such as "mobile web" in the group's name, not in `channels`. A `channelGroupId` is 1–64 letters, digits, dots, dashes or underscores, unique within the campaign. Over REST (`POST` or `PUT /api/v2/buyer/campaigns`), send the saved shape; there's no preset shorthand: ```json theme={null} { "channelGroups": [ { "channelGroupId": "mobile-web-display", "name": "Mobile web display", "source": { "kind": "preset", "presetId": "mobile_web_display", "presetVersion": 1 }, "inventory": { "channels": ["display"], "propertyTypes": ["website"], "deviceTypes": ["mobile"], "formatKinds": ["image", "html5", "display_tag", "image_carousel", "native_in_feed", "sponsored_placement", "responsive_creative", "custom"] } } ] } ``` A custom group's `source` is `{ "kind": "custom" }`. The media-buy batch's `campaign.create` takes the same saved shape. ## Assign products to a group When a campaign defines groups, every staging call names one: * `save_media_buy` (products or a proposal): `channelGroupId` applies to everything staged in that call. * `POST /api/v2/buyer/media-buys/batch`: `channelGroupId` on each selection. A missing or unknown `channelGroupId` is refused with the campaign's group ids, and a campaign without groups refuses one. Each draft buy records the `channelGroupId` and `channelGroupName` that created it. [Auto-select](/buy/autonomy-settings#auto-select-products) assigns each product to the first group whose channels it carries. Groups are immutable once used: * A group a staged buy references can't be removed or redefined (`409 CONFLICT`: "Add a new group instead."). Add a new group. * Define groups before the campaign's first buy is staged: adding groups to a campaign that already has an ungrouped buy is refused (`409 CONFLICT`). ## Report by group Use `get_delivery` with the `channel_group` dimension: ```json theme={null} { "report": "campaign_delivery", "metrics": ["impressions", "spend", "clicks"], "dimensions": ["channel_group"], "range": { "startDate": "2026-09-01", "endDate": "2026-09-30" }, "filters": { "campaignId": "cmp_…" } } ``` Add `filters.channelGroupId` to read one group. Buys staged without a group roll up under a `null` channel group; they're never guessed from names or products. Channel groups answer "which inventory selection did the buyer ask for?" Campaign [targeting](/buy/targeting) answers "who, where or when should it reach?" Keep them separate even when both mention a dimension such as device. ## Related * [Media buys and packages](/buy/media-buys-and-packages) * [Autonomy and auto-select](/buy/autonomy-settings) * [Reporting](/buy/reporting)