Source.schain

The SupplyChain object listing every system that sold or resold this request, with a flag for whether the list reaches back to the inventory owner. A core field since 2.6; earlier integrations send it as source.ext.schain.

CurrentobjectRecommendedSince 2.6-202204

Field facts

Path: source.schain
Object: Source
Type: object
Requirement: Recommended
Added: OpenRTB 2.6-202204
Spec section: 3.2.2

How it is used

Buyers walk the nodes in order, check each asi and sid pair against that system's sellers.json, and match the first node against the publisher's ads.txt. Supply path optimization tools score or block paths on the result. Each system that forwards the request appends exactly one node for itself and leaves earlier nodes untouched. On 2.6 traffic send the chain at source.schain only; on 2.5 traffic, source.ext.schain is the established location.

Example

Where the field sits in a payload, with everything else left out:

{
  "id": "req-1",
  "source": {
    "schain": {
      "ver": "1.0",
      "complete": 1,
      "nodes": [
        {
          "asi": "ssp.example",
          "sid": "pub-4791",
          "hp": 1
        }
      ]
    }
  }
}

Common mistakes

Leaving the chain at source.ext.schain on a request declared as 2.6; the validator reports the old path as moved.
Sending the chain at both paths lets the copies drift apart, and the validator warns with openrtb.schain.duplicate_location.
Rebuilding the chain from scratch instead of appending to it drops the upstream nodes, which then forces complete to 0.

Version history

Added in OpenRTB 2.6-202204, and present in the latest snapshot. The table shows how each version's spec text types the field.

Versions	Type in the spec	Required	Deprecated
2.6-202204	Added in the first 2.6 release, published without a structured text archive; the 2.6-202210 republication is the first tagged text.
2.6-202210 to 2.6-202606	object	Recommended	No

Versioned rules that name this field

openrtb.2.6.network_channel_supplychain_eids OpenRTB 2.6 added network, channel, supply-chain, and extended-ID object families.

Related fields

Other Source fields

For a walkthrough of the whole object, read Supply chain (schain).