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