In the 1980s, Horst Rittel developed the Issue-Based Information System, a hypertext environment for the structured discussion of design issues. This system uses a stringent classification scheme to organize the data. There are three node types (issues, positions, arguments) and nine link types (responds-to, questions, supports, objects-to, specializes, generalizes, refers-to, replaces). These elements are designed to be used in the analysis of "wicked problems." According to Conklin:
Wicked problems lack a definitive formulation; their problem space cannot be mapped out without understanding the solution elements; in short, the only way to really understand a wicked problem is to solve it. (24)
As of 1987, IBIS ran on Apple computers, but did not support graphics, searches, paths, maps, or link attributes.
Begeman and Conklin later developed gIBIS, a graphical version of IBIS, running on Sun workstations. This software divides the display into four fixed windows, simultaneously displaying a map (global and local), index, node contents, and control panel (256). gIBIS is a sophisticated environment which includes clusters (here called subnets), context-sensitive menus, multiple indexes (subject, author, keyword, title), user configurations, link filtering, simple queries, multi-user access, and pointers to external objects.
The authors have noted some difficulties with this system, most notably the problem of cognitive overhead engendered by the high degree of structure.
Hashim has published the code (written in Turbo Prolog) for MicroIBIS, a PC implementation of IBIS which includes maps, anchors, clusters, versioning, filters, user configuration, and node attributes. He also provides a thorough discussion of wicked problems (224).