----------------------------Original message---------------------------- I have the National Ocean Survey publication dated "Revised: October 3, 1977" entitled "Nautical Chart Number Conversion Table" which indicates that "effective July 1, 1974, the National Ocean Survey, in cooperation with the Defense Mappping Agency Hydrographic Center, began a new national chart numbering system designed to provide a uniform method of identifying charts. Effective October 1, 1977, ordering and dis- tribution will be based on the new number." The example you used # 5984, appears as # 18587 in this publication. Stan Stevens at UC Santa Cruz [log in to unmask]