written by Bill Brown, Terry Baker, Mark Astley, and David Gerdes, U.S. Army Corps of Engineers Research Laboratories, Champaign, Illinois and UI GMS Laboratory, Urbana, IL.
Original documentation written by Terry Baker (spring 1995), and updated by Mark Astley, based on a document written by Bill Brown.
Program and documentation (2004) updates by Bob Covill, Tekmap Consulting.