ads.txt for a site with no ads
Don Marti: “since there’s a lot of malarkey in the online advertising business, I’m putting up this file [on my website] to let the advertisers know that if someone sold you an ad and claimed it ran on here, you got burned.”
The format is defined in a specification from the IAB Tech Lab. The important part is the last line. The placeholder is how you tell the tools that are supposed to be checking this stuff that you don’t have ads.