All knowledge has to be plugged into this structure. The curriculum is a network of goals, connected by prerequisite links. The problems . A goal defines a skill by specifying a set of problems that the learner must be able to solve. The interface .
Learners solve problems through a goal-specific interface.
A goal includes a hypertext chapter that the learner may explore freely and where he can find any information relative to the skills he must acquire. This representation of goals results from our design principles. The designer's task is not automated. For each goal, the developer defines one or more application frames , i.e. windows wherein the learner will solve problems. It gathers all the information that defines a situation, i.e. the window, the command tables, etc.