Absolutely. It usually tends to be either more visible, or less visible though - some pdf files have a literal watermark on the pages, while other formats like

Absolutely. It usually tends to be either more visible, or less visible though - some pdf files have a literal watermark on the pages, while other formats like epub contain a guid or other watermark content in the source (epub is zipped xhtml) https://gizmodo.com/harpercollins-is-now-using-digital-watermarks-to-stop-e-1635220938 https://gizmodo.com/harpercollins-is-now-using-digital-water... https://goodereader.com/blog/e-book-news/everything-you-need-to-know-about-social-drm-for-ebooks https://goodereader.com/blog/e-book-news/everything-you-need... Amusingly, I believe if you use calibre's ebook conversion to replace stylesheets and add toc, it may also actually remove those markers that have no actual content and only exist to provide a unique ID.