Procedural knowledge in medicine is embedded in Clinical Practice Guidelines whose textual condition makes it difficult to share and to reuse. Several languages for formal definition of clinical practice guidelines have been proposed to overcome these difficulties. In order to deal with the huge amount of medical situations, these languages use to be extensive and complex in such a way that they, and the knowledge they are used to represent, are arduous to understand and to manage by non-trained general practitioners. The SDA* model is introduced as an alternative language that promotes representation capability and simplicity in such a way that not only computers, but also health care professionals are able to understand and manage easily without any sort of training. Here, a description of this model from a set theory perspective is provided.