Flexible Diff-ing in a Collaborative Writing System
http://doi.acm.org/10.1145/143457.143473
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Neuwirth, Christine M., Ravinder Chandhok, David S. Kaufer, Paul Erion, James Morris and Dale Miller
Computer Supported Cooperative Work
1992

Abstract:

Discusses the use of computer-generated information about what has been revised in the display of editing in word processors.