The body of literature dealing with the environment, albeit a synthetic or conglomerate science, did not have an organizing classification structure or system until the appearance of this publication, to the best of the authors' knowledge. The Environmental Classification System is an enumerative hierarchical classification with an alphanumeric, ordinal notation. The notation resembles that of the Library of Congress Classification, but was not derived from, nor is it in any other way beyond resemblance, related to it. The Classification has 22 main subject groups.