  SOFTSUSY is a program which accurately calculates the spectrum of
superparticles in the CP-conserving Minimal Supersymmetric Standard Model
(MSSM), with a full flavour mixing structure. The program solves the
renormalisation group equations with theoretical constraints on soft
supersymmetry breaking terms provided by the user. Weak-scale gauge coupling
and fermion mass data (including one-loop finite MSSM corrections) are used as
a boundary condition, as well as successful radiative electroweak symmetry
breaking. The program can also calculate a measure of fine-tuning. The program
structure has been designed to easily generalise to extensions of the MSSM.
This article serves as a self-contained guide to prospective users, and
indicates the conventions and approximations used.
