Derived from the International Standards Organization code for a business that meets expected standards. As a slang term, it's used as a pejorative to denote something that's typical, by-the-numbers, formulaic and/or cliché.
"If you take out all the pop-culture references, Ready Player One is really just the same ISO 9001 standard 'Young-Adult Teen Dytopia' story that's been made a hundred times already."