The North American Stratigraphic Code, hereafter referred to as the Code, "represents but a stage in the evolution of scientific communication" (North American Commission on Stratigraphic Nomenclature, 1983, p. 841). It requires continued revision to adapt and better meet the present and emerging needs of the profession. The North American Commission on Stratigraphic Nomenclature (NACSN) is the body of scientists entrusted with the responsibilities of recommending procedures for classifying and naming stratigraphic and related units and of considering proposal for amendment to the Code.

In 1994, the NACSN decided to address various inconsistencies and imperfections detected in the Code. Chairman Donald G. Cook appointed an ad hoc committee consisting of Lucy E. Edwards, Robert H. Fakundiny, R. Michael Easton, and Ismael Ferrusqu\ \ia, chaired by the latter, to look into consistency, clarity, and simple updates and to make recommendations. At about the same time, the Association of Earth Sciences Editors proposed updating of the Code with respect to electronic publishing. Another ad hoc committee of the NACSN was appointed in 1996 to deal with biostratigraphic units (Note 64, this volume). An additional ad hoc committee has been appointed to consider diachronic units.