ZOG consisted of "frames" that contained a title, a description, a line containing ZOG system commands, and selections (menu items) that led to other frames.3 ZOG pioneered the "frame" or "card" model of hypertext later popularized by HyperCard. In such systems, the frames or cards cannot scroll to show content that is part of the same document but held offscreen. Instead, text that exceeds the capacity of one screen must be placed in another (which then constitutes a separate frame or card)
The ZOG database became fully functional around 1977. Beginning in 1980, ZOG was ported from DEC VAX version (written in an experimental language called "L*") to the Pascal-based Three Rivers PERQ workstation and was used for a shipwide local area network on the American aircraft carrier USS Carl Vinson. In 1981, Rob Akscyn and Donald McCracken, two principals from the ZOG project, founded Knowledge Systems to develop and market a commercial follow-on to ZOG called KMS ("Knowledge Management System").4
An example of syntax from one dialect of ZOG:5
McCracken, DL; Akscyn, RM (2003), Experience with the ZOG human-computer interface system, CMU, doi:10.1184/R1/6605399.v1 https://figshare.com/articles/Experience_with_the_ZOG_human-computer_interface_system/6605399 ↩
Van Matre, N. H.; Moy, M. C.; McCann, P. H. (Dec 1984). "1.3 Objective". The ZOG Technology Demonstration Project: A System Evaluation of USS CARL VINSON (CVN 70). p. 2. Archived from the original on January 1, 2020. https://apps.dtic.mil/docs/citations/ADA158084 ↩
"Zog form entry", The ZOG Technology Demonstration Project: A System Evaluation of the USS Carl Vinson (CVN 70) (PNG), December 1984. https://commons.wikimedia.org/wiki/File:Zog-form-entry.png ↩
Robertson, CK; McCracken, DL; Newell, A (1979), "The ZOG approach to man-machine communication", Interim Report Carnegie-Mellon Univ (technical report), Pittsburgh, PA, US: Carnegie-Mellon University, Department of Computer Science, Bibcode:1979cmu..rept.....R, CMU-CS-79-148. /wiki/Bibcode_(identifier) ↩