A zettelkasten consists of many individual notes with ideas and other short pieces of information that are taken down as they occur or are acquired. The notes are numbered hierarchically, so that new notes may be inserted at the appropriate place, and contain metadata to allow the note-taker to associate notes with each other. For example, notes may contain tags that describe key aspects of the note, and they may reference other notes. The numbering, metadata, format and structure of the notes is subject to variation depending on the specific method employed.
it is apparent that the unfolding of the design process assumed a distinctly episodic structure, which we might characterize as a series of related skirmishes with various aspects of the problem at hand.
As the scope of the problem became more determined and finite for the designer, the episodic character of the process seems to have become less pronounced. During this period a systematic working out of issues and conditions took hold within the framework that had been established. This phenomenon is not at all surprising when we consider the fundamental difference between moments of problem solving when matters are poorly defined and those with clarity and sufficiency of structure.
Within the episodic structure of the process, the problem, as perceived by the designer, tends to fluctuate from being rather nebulous to being more specific and well-defined. Furthermore, moments of "blinding" followed by periods of backtracking take place, where blinding refers to conditions in which obvious connections between various considerations of importance go unrecognized by a designer.