Glossary: app-ads.txt, sellers.json and schain terms

A

Ad network: A company that sells inventory from many apps, often with its own SDK and its own demand.
ads.txt: The IAB Tech Lab file a website publishes at /ads.txt listing the ad systems and accounts allowed to sell its web inventory. app-ads.txt uses the same syntax. Read the guide
Advertising system domain: Field #1 of an app-ads.txt line: the canonical domain the SSP or network asks publishers to use, the domain whose /sellers.json describes its sellers. Read the guide
app-ads.txt: app-ads.txt is the file a developer publishes on its website listing every ad system and account allowed to sell its apps' inventory. Defined by the IAB Tech Lab's app-ads.txt specification, an extension of ads.txt for apps: verifiers find the file through the developer website in the store listing. Read the guide

B

BOTH (seller type): The account is used both for inventory the seller owns and for inventory it resells, so sellers.json alone cannot confirm the relationship of a given line. Read the guide
Bundle ID: The platform identifier of an app, such as com.example.game on Android. It is what a bid request carries in app.bundle.

C

Certification authority ID: Optional field #4 of an app-ads.txt line, usually the network's TAG ID. ads.txt 1.1 says identifiers in sellers.json supersede it and that it may be deprecated. Read the guide
complete (schain): complete = 1 means the schain lists every seller back to the owner of the app; 0 means at least one seller did not add itself. Read the guide
Confidential seller: A sellers.json entry with is_confidential = 1: the name and domain are hidden. The entry must still be listed. Buyers cannot tell who is paid. Read the guide
Confirmed both ways: Lines listed in sellers.json with the right type AND whose seller domain points back to this publisher (DIRECT) or to a known reseller (RESELLER). For DIRECT lines, the seller's domain in sellers.json should be the publisher's own domain (or its OWNERDOMAIN). Read the guide
CONTACT: An optional variable with a way to reach whoever maintains the file. Read the guide
CTV: Connected TV: apps on TV devices and platforms such as Roku, Fire TV, Apple TV, Android TV and smart TVs. Their app stores link to the developer's app-ads.txt like mobile stores. Read the guide

D

Delisted app: The app was not found on its store on two checks on different days. Its app-ads.txt may still be online. Inventory still offered under a delisted app's identifier deserves a closer look.
Developer website: The URL in the app's store listing. Verifiers derive the app-ads.txt location from its host name: www. and m. are dropped, a subdomain is tried first and then its parent domain. Read the guide
DIRECT: DIRECT: the app's own publisher holds this account with the ad system and is paid by it directly. The line should match a PUBLISHER entry in the network's sellers.json. Read the guide
DSP: Demand-side platform: software that buys inventory for advertisers and is the main consumer of app-ads.txt, sellers.json and the schain. Read the guide

E

Exchange: A marketplace where SSPs, networks and DSPs trade impressions. In app-ads.txt it appears like any other ad system, by its domain.

H

Hop: A hop is one step from the app to whoever sells it. Hop 1 is the app-ads.txt line; deeper hops follow intermediaries through their own sellers.json, up to 4. Hop 1 is the line in app-ads.txt; each further hop follows an intermediary through its own network's sellers.json. Read the guide
hp (schain): Set to 1 when the node is in the flow of payment. Version 1.0 of the SupplyChain object requires 1; a proposed 1.1 adds hp = 0 for parties that handle the request without being paid for the inventory. Read the guide

I

In-app bidding: Mediation that runs a real-time auction among networks instead of calling them one after another in a fixed order (a waterfall).
INTERMEDIARY (seller type): The seller does not own the inventory, or the network does not pay the owner directly: a reseller, an ad network or a mediation company. Read the guide
Invalid traffic (IVT): Impressions not from a real person with real intent (bots, hidden placements, spoofed apps). app-ads.txt does not detect IVT; it only says who may sell. Read the guide
INVENTORYPARTNERDOMAIN: An ads.txt 1.0.3 variable for shared inventory, mostly CTV: it points to a content partner whose ads.txt lists the sellers authorised for the partner's share. Followed one hop only. Read the guide
is_passthrough: An optional sellers.json flag (default 0) for a seller that passes inventory from its source on to the next platform while keeping its own account there. Few networks set it. Read the guide

M

MANAGERDOMAIN: An ads.txt 1.1 variable naming the primary or exclusive company that monetizes the inventory, optionally per country (ISO 3166-1 alpha-2 code). Read the guide
Mediation: An SDK layer in the app that calls several networks and bidders for each impression and picks the best price. Each network it calls needs its own app-ads.txt line.

O

OpenRTB: The IAB Tech Lab protocol for real-time bid requests and responses. The schain sits in source.schain from OpenRTB 2.6 (source.ext.schain in 2.5). Read the guide
OWNERDOMAIN: An ads.txt 1.1 variable naming the business domain of the company that owns the app or site. It should equal the domain that company has in the networks' sellers.json. Read the guide

P

Placeholder record: The line "placeholder.example.com, placeholder, DIRECT, placeholder", which tells crawlers the file is deliberate and that no seller is authorised. Read the guide
PUBLISHER (seller type): The network pays this seller directly and the seller owns the inventory sold under the account. Read the guide
publisher.id: The OpenRTB field that usually carries the seller account ID; verifiers compare it with field #2 of app-ads.txt. Read the guide

R

RESELLER: RESELLER: a third party holds this account and is authorised to resell the app's inventory. The line should match an INTERMEDIARY entry in the network's sellers.json. Read the guide

S

Seller ID (account ID): The account a publisher or reseller holds with a network. The same value appears as field #2 in app-ads.txt, seller_id in sellers.json and sid in the schain, and normally as publisher.id in the bid request. Read the guide
seller_type: From the ad system's sellers.json: PUBLISHER (owns the inventory), INTERMEDIARY (resells it) or BOTH. Required on every sellers.json entry. Compared with the relationship in app-ads.txt to check a line. Read the guide
sellers.json: sellers.json is the file an ad system publishes listing every seller account it pays, with the seller's type (PUBLISHER, INTERMEDIARY or BOTH) and domain. Published at /sellers.json on the domain the network uses in app-ads.txt (IAB Tech Lab sellers.json 1.0). Read the guide
Spoofing: Offering inventory under an app's identifier by someone not authorised to sell it. app-ads.txt exists to make spoofing detectable: the seller account will not be in the app's file. Read the guide
SSP: Sell-side platform: software that sells publishers' inventory to many buyers, usually through real-time auctions. SSPs publish sellers.json.
Stale seller: A seller ID declared in app-ads.txt that the ad system's sellers.json no longer lists (or never did). Buyers usually drop these paths. The commonest cause is a partner that closed or renumbered the account while the publisher's file kept the old line. Read the guide
Store ID: The identifier of an app inside one store, such as the numeric App Store ID.
storeurl: The app's store listing URL in the bid request (app.storeurl). Verifiers use it to find the developer website and so the app-ads.txt. Read the guide
SUBDOMAIN: An ads.txt variable pointing crawlers to a subdomain's own file. It is unused in app-ads.txt and ignored there. Read the guide
Supply path: The chain of sellers between an app and a buyer. Declared in app-ads.txt and sellers.json; reported per request in the schain. Read the guide
Supply path optimization (SPO): A buyer's practice of buying an impression through as few and as direct sellers as possible, using app-ads.txt, sellers.json and the schain to tell paths apart. Read the guide
Supply path score: Supply path score, 0 to 100: how short and clean the declared path is (DIRECT share, lines confirmed both ways, live sellers, number of resellers, chain depth, hidden sellers). 70+ clean, 40 to 69 mixed, under 40 risky. Computed by Stoqlab; the formula is on the methodology page. Read the guide
SupplyChain node: One entry in the schain: the ad system's domain (asi), the seller account (sid), whether the seller is in the payment flow (hp) and optionally the request ID (rid). Read the guide
SupplyChain object (schain): An OpenRTB object that travels with a bid request and lists every seller that handled it, one node per seller, so a buyer can see the whole path from the app to the request it received. Read the guide

T

TAG: The Trustworthy Accountability Group, an industry certification body. Its TAG ID is the most common value in field #4.

V

Verified line: Lines whose account the ad system's sellers.json lists with a type that matches the declared relationship (one direction). A line that passes this check is authorised as far as the public files can say; it says nothing about the traffic itself. Read the guide

Supply-chain terms, defined

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