The advent of pen-based interfaces has led to the development of many applications concerning the analysis of a drawn shape. But a drawing is not only a shape. It is also all the gestures which constitutes the drawing activity, as well as their planning. Pen-based interfaces give us the possibility to analyze this dimension of sketching. We call this kind of analysis: procedural analysis. In this article, we will show how to identify the privileged drawing procedures of users by identifying a constant pattern despite a huge within-drawer variability in drawing procedures. After stating how to extract this constant pattern, we shall show how we can use those results into a drawing-based user identification method.