Taxonomy is defined as the “branch of science concerned with classification, especially of organisms; systematics; the classification of something, especially organisms; a scheme of classification” (Oxford Dictionary, 2013). Within a taxonomy, the domains are “a sphere of knowledge, influence, or inquiry”; and the classes are “a group, set, or kind sharing common attributes” (Merriam-Webster, Inc., 2009). We can adapt the definition for a nursing diagnosis taxonomy; specifically, we are concerned with the orderly classification of diagnostic foci of concern to nursing, according to their presumed natural relationships. Taxonomy II has three levels: domains, classes, and nursing diagnoses. Figure 3.3 (p. 58) depicts the organization of domains and classes in Taxonomy II; Table 3.1 (pp. 66–78) shows Taxonomy II with its 13 domains, 47 classes, and 235 current diagnoses. The Taxonomy II code structure is a 32-bit integer (or if the user’s database uses another notation, the code structure is a five-digit code). This structure provides for the stability, or growth and development, of the taxonomic structure by avoiding the need to change codes when new diagnoses, refinements, and revisions are added. New codes are assigned to newly approved diagnoses. Retired codes are never reused. Taxonomy II has a code structure that is compliant with recommendations from the National Library of Medicine (NLM) concerning healthcare terminology codes. The NLM recommends that codes do not contain information about the classified concept, as did the Taxonomy I code structure, which included information about the location and the level of the diagnosis. The NANDA-I terminology is a recognized nursing language that meets the criteria established by the Committee for Nursing Practice