Last year about this time, the Interactive Advertising Bureau (IAB) Tech Lab launched its ads.txt project to prevent fraudulent selling of website ad inventory.

This week, the Tech Lab is releasing a proposed spec for extending ads.txt, which is now widely adopted, to mobile apps. The proposal is open to public comments over the next 30 days.

Essentially, SVP and General Manager Dennis Buchheim explained to me, it’s the same ads.txt, but with a pointer from apps. For web inventory, the ads.txt file, which lists those exchanges and others that are authorized to sell space on a given site’s pages, normally resides in the root folder of a website.

In the newest proposal for apps, the ads.txt file for a given app will also often reside on an associated website, with some reference from the app to the file location.

Travelocity’s app, for instance, would point to its ads.txt file on, say, the Travelocity site. In fact, Buchheim noted, the ads.txt file might be same for both the Travelocity website inventory and the web app inventory, if the sellers are the same for both.

The IAB’s proposed spec suggests three ways for that pointer to work. In one approach, it could employ a “bundled ID” that is sometimes used as an identifier in app stores. The bundled ID, in conjunction with the web domain, would point directly to the ads.txt file located in that domain.

A second approach is that the app store could provide a new API that offers the ads.txt file for each app, bypassing an accompanying web domain. Or, Buchheim suggest, there might eventually be one or more independent services that supply the ads.txt files.

In any case, he made clear that this proposed spec is “an invitation to respond” for app stores and third-party party vendors.

The link to an ads.txt file for a given app can also reside inside the OpenRTB request for an ad, so everyone in chain for an ad request can see who is authorized to sell that space.

Last month, the Tech Lab launched an aggregation service for Ads.txt.