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Path: utzoo!watmath!clyde!cbosgd!ihnp4!mecc!sewilco
From: sewilco@mecc.UUCP (Scot E. Wilcoxon)
Newsgroups: net.crypt
Subject: Laser printers simplify positional coding
Message-ID: <418@mecc.UUCP>
Date: Mon, 10-Feb-86 11:15:12 EST
Article-I.D.: mecc.418
Posted: Mon Feb 10 11:15:12 1986
Date-Received: Wed, 12-Feb-86 05:58:04 EST
Reply-To: sewilco@mecc.UUCP (Scot E. Wilcoxon)
Organization: MN Ed Comp Corp, St. Paul, MN
Lines: 15
Keywords: laser printer positional code scanner

The spacing between characters can be used as a code.
I'm sure this has been done before with older technologies.
Laser printers with resolutions in fractions of an inch make
positional coding almost simple.  Incidentally, such codes
could also be mechanically read with a page scanner.

The application which prompted my thoughts is the widespread
use of numbered copies of documents, and the occasional leaks
of them.  If each copy of a document has a document number
coded by positional coding, a leaked photocopy might show
the coded number and help find the source of the leak.
-- 

Scot E. Wilcoxon  Minn. Ed. Comp. Corp.            quest!mecc!sewilco
45 03 N / 93 15 W   (612)481-3507 {ihnp4,mgnetp}!dicomed!mecc!sewilco