  The HORACE suite of programs has been developed to work with large
multiple-measurement data sets collected from time-of-flight neutron
spectrometers equipped with arrays of position-sensitive detectors. The
software allows exploratory studies of the four dimensions of reciprocal space
and excitation energy to be undertaken, enabling multi-dimensional subsets to
be visualized, algebraically manipulated, and models for the scattering to
simulated or fitted to the data. The software is designed to be an extensible
framework, thus allowing user-customized operations to be performed on the
data. Examples of the use of its features are given for measurements exploring
the spin waves of the simple antiferromagnet RbMnF$_{3}$ and ferromagnetic
iron, and the phonons in URu$_{2}$Si$_{2}$.
