The Alexandrian form

This is form was originally introduced by Christopher Alexander who is the "founder" of design patterns. This form of presentation consist of at least three sections Problem, Context and Solution. The problem section describes the problem at hand, the Context section describes the situation in which the problem occurs, and Solution describes the solution to this problem. [1]

This is patter is "generative"  It guides the intended user to generate his or her solution from the pattern description. 

Below is an example of Alexandrian form for pattern definition.

Problem
    Avoid getting your household items from becoming wet.

Context
    You live in the area that has precipitation.

Solution
    Your house has a roof.