As the below interrelationship diagram suggests, it Is complementary to other tools of quality and continuous improvement like the affinity diagram to give continuity to the consolidation of information or the diagram of fish thorn or the tree to deepen in the exploration of the causes. SDL is a formal, structured language that avoids the ambiguity inherent in using common English to define or specify a system. The repository consists of elements that are modified by attributes and related to other elements. This structure corresponds to the object-oriented approach. Elements are represented as objects, with the attributes stored as data within the objects. The relationships then define the interaction between objects. In the following diagram, the SDL is referred to as a schema (or the project metadata). The diagram below illustrates a subset of the basic schema, showing some primary systems engineering classes and their relationships.