[throwanem]

It's possible to implement a purely informational watermark lots of ways, but no such watermark long survives wide awareness of its use. To know how it works is to know how to defeat it.

This specific scheme is also not remotely novel; I once saw it implemented, something like six or eight years back, in an effort to quell leaks to an industry rag with a habit of posting paragraph-length excerpts verbatim. They also did this with some of the watermarked emails, having stripped the watermarking whitespace before publication.