All CBB's implicitly contain a number of basic elements. These are usually not included in the information models of the individual building blocks, but are supposed to be present. These are concepts that are of a more technical nature, often have little or no clinical relevance, but are necessary for the sake of clarity and readability of the information. In those cases where these elements are of clinical significance, they will usually be explicit in the information models. An example of this is an AGB number as an identification number for a health professional.