Isn't this just run-of-the-mill watermarking? Is there anything novel about this?
No, we don't add watermarks, our marks are invisible, you can't remove them and they are on the whole document, in each line. And for instance, if somebody decides to leak this enriched with anti-leak marks document and publishes it in open sources, our system will determine the name of the violator. We have an implemented on our platform investigation tool, where you can upload compromised documents and find the leaker.