Ad Stack Declaration

Ad Stack Declarations enable publishers to explicitly define traffic and connection data by property, country, seller, and placement, providing an authoritative alternative to the ads.txt-based ad selection graph. This allows for a more accurate and representative model of the ad tech supply chain across digital properties.

Benefits

Participating publishers contribute to a more complete and representative view of their supply chain’s climate impact within the Scope3 ecosystem.

Use cases

Ad stack declaration allows for emissions modeling tailored to specific scenarios, whether by property, country, seller, or placement. For instance:

App Publisher A might use different vendors domestically and internationally.
Web Publisher B might have a dedicated supply chain for their sports section.
CTV Publisher C might have separate monetization strategies for Android TV than Roku.

Expected inputs

Use case the ad stack applies to

Field	Description	Example
`ad_stack_name`	The name to display in Scope3's CSP when representing the ad stack.	`GB monetization`
`inventory_ids`	The list of properties this ad stack applies to.	`cnn.com`
`channel`	The channel this ad stack applies to.	`web`
`countries`	The list of countries this ad stack applies to	`GB`
`sellers`	The list of sellers this ad stack applies to	`All`
`placements`	The list of placement IDs this ad stack applies to. GPIDs are preferred.	`All`

The list of steps used in the ad stack

Field	Description	Example
`step_name`	The name to display in Scope3's CSP when representing the step	`Header Bidding`
`step_order`	The order of this step in relation to other steps. Steps ran in parallel should have the same step_order.	`1`
`tool`	The tool used to conduct the step (e.g. Google Ad Manager, Amazon TAM, Prebid.js, Xandr PSP...).	`Prebid.js`
`occurrence_percentage`	The percentage of traffic where the tool is used for the specified use case. This typically represents the ratio of ad requests sent to the tool to the total number of ad opportunities for that use case. For example, if Prebid.js is called for all traffic but "ad blocked" traffic which represents 8% of total traffic, the occurence_percentage should be 92%. This percentage can possibly be greater than 100% if the tool is called more than once per ad impression on average.	`92%`

For each step: The list of connected Ad Tech platforms

Field	Description	Example
`ad_tech_platform`	The tool used to conduct the step (e.g. Google Ad Manager, Amazon TAM, Prebid.js, Xandr PSP...).	`Pubmatic`
`occurrence_percentage`	The percentage of traffic seen by tool that makes it to the connected Ad Tech platform. This typically represents the ratio of ad requests sent to the Ad Tech Platform to the total number of ad requests sent to the tool that the platform connects through. This percentage can possibly be greater than 100% if the platform is called by the tool more than once per ad request on average (e.g. bid duplication).	`57%`

Example input

Below is a sample YAML configuration representing an ad stack declaration for a specific property and country.

ad_stack_config:
  name: Outside of the US
  organization:
    name: Warner Bros Discovery
  default_for:
    property_id: 1195832
    country: GB
steps:
  - order: 1
    name: Header Bidding
    tool: Prebid.js
    occurrence_pct: 92
    atps: 
      - name: Index Exchange
        occurrence_pct: 100
      - name: Pubmatic
        occurrence_pct: 57
      - name: Xandr Monetize
        occurrence_pct: 40
  - order: 2
    name: Ad Server and Open Bidding
    tool: Google Ad Exchange (AdX)
    occurrence_pct: 100
    atps:
      - name: Index Exchange
        occurrence_pct: 20
      - name: Pubmatic
        occurrence_pct: 36
      - name: Nexxen
        occurrence_pct: 71
      - name: Magnite DV+
        occurrence_pct: 10
  - order: 3
    name: Waterfalling to Xandr
    tool: Xandr Monetize
    occurrence_pct: 16
    atps: []
  - order: 3
    name: Waterfalling to Nexxen
    tool: Nexxen SSP
    occurrence_pct: 8
    atps: []

Ingestion process & expected outcome

Currently, all ad stack declarations must be reviewed and uploaded by a Scope3 Solutions consultant. To initiate this process, contact your Customer Success representative or Scope3 Support.

Once uploaded, the ad stack will be incorporated into Scope3’s emissions model starting from the first day of the following month, replacing ads.txt-based assumptions for the defined use cases. The ad stack will also be represented in the ad selection diagram in the property pages in Scope3's CSP.