[adityaathalye]

Hm, you made me think about non-printing characters as metadata, which is of course immediately lost on printing and therefore does not round trip between digital and printed versions.

Many nonprinting characters imply some directive; line break (hard-wrap the text here, but this is not a paragraph), page break (let the rest of the page be blank, start the next paragraph overleaf), EOL (file over, bye bye), nonbreaking space (keep these two words together, always, till death do them part).

This is out-of-band information spliced in-band (with the text corpus), which a computer program can "see", but a person can't.