Prototypes in Technical Writing: What are They?
http://jerz.setonhill.edu/design/usability/prototype.htm

Jerz, Dennis G.
University of Wisconsin-Eau Claire
2000

Abstract:

A prototype is, generally speaking, a preliminary model of a larger, more detailed object. In technical writing, a prototype might be a full table of contents (with summaries for each major section) and one or two complete chapters. If conducting a survey is an important part of your project, your prototype might be a complete survey of a small number of subjects, designed to iron out the kinks in the questions you want to ask. A good prototype will help you identify flaws (such as incomplete research or mistaken assumptions) before you have multiplied their harmful effects by investing additional effort in them. A sculptor makes a scale model in clay -- a prototype -- before chiseling away at a full-sized chunk of marble. It it much easier to fix major mistakes in clay than it is to throw away a ruined chunk of marble and start over again.