The Cross-Referenced Editing Facility (CREF) is a prototype of a specialized text and graphics editor which was developed originally as a tool for use in analyzing the transcripts form psychological experiments (known as protocols), but which was also used to investigate more general hypertext design issues. Much of the interactive feel of CREF reflects the style of use and programming of the Symbolics Lisp machine, on which it was built. Chunks of text, called segments, constitute the nodes in the system. Segments are arranged in linear series, and can have keywords and various kinds of links to other segments. The notion of a linear set of segments is natural to the protocol analysis problem, since the first step which such protocols is to segment them into the episodes of the experiemental session. (Conklin, 1987)