Note that you just identified the "otherwise anonymous" engineer. I2O
could look at these numbers and figure out which copy of the specs you
have. (In this case I imagine they already know which copy was
"dropped", assuming they care, assuming they have multiple independant
copies to begin with. It has been there quite some time last I
checked.)
I don't think there is any simple way to prevent tracking of such
documents. They can not only insert whitespace, but typos, and even
flip perfectly legitimate words between two spellings.
There is a grey area in the color coding of the disc drive.
There is a gray area in the colour coding of the disk drive.
A spell checker or even a careful proof reader would not catch these
flips most of the time, and this is straight text... Thus even
printing a document is not a safety feature, and as was pointed out,
"pdf", "ps", et al could be given minor tweaks to make the horizontal
rules longer/shorter, fiddle with the top margin (a perfectly
decodable "hidden message protocol" on a long document, assuming it
doesn't get hand photocopied or something.)
hidden message protocol, or subliminal channel -
you can hide a bit of information in every "flippeable" feature
of a document, or 7/8 of a bit if you want error detection ;), so on
a long document, you could even write the person's name into the text,
assuming you have automatic "text feature flippability detection".
--kmb203@psu.edu----------------Debian/GNU--1.3---Linux--2.0.30---
OK, so you're a Ph.D. Just don't touch anything.