Neutron instrument simulations in the next millennium

The Neutron Instrument Simulation Package (NISP) is available on the world-wide web at URL http://strider.lansce.lanl.gov/NISP/Welcome.html. With more than 20 years of development, there is a certain amount of maturity in the code, but also the potential for a great deal of growth. As requirements for more sophisticated simulations grow, NISP can be expanded or modified to meet those needs. This report describes features of the NISP structures that make it possible for users to contribute algorithms. Any interaction that can be coded as a Fortran-callable subroutine can be included as a region type in the simulations. New ideas are always solicited, and may be sent by e-mail to