A package for analysing lSR data has been developed for the PC running Microsoft Windows operating systems (Windows 95, 98 and NT4). Some of the key points considered in the design of the program were that it should run on a typical Windows PC, that it should directly read the binary "les produced by muon data acquisition systems, that it should be equally easy to analyse data on-line and o!-line and that appropriate features should be included for both pulsed and continuous muon sources.
This program simulates the evolution of muon spins interacting with nearby nuclei or electrons, using the density matrix method. Interactions include dipolar, hyperfine, quadrupolar and Zeeman energy. It can model RF resonance, or relaxation processes caused by changes of site or charge state.