Each required operation is performed by a separate module (a set of subprograms).
HORIHX or HORISQ takes a source distribution in the transverse plane, given at the center and corners of each fuel bundle in hexagonal or square geometry, and transforms it into (r,theta) or radial geometry. In the latter case, the output distribution may be averaged in the azimuthal direction or azimuthal maxima may be obtained.
FOUR takes an axial distribution, specified as a histogram, and approximates this with a Fourier series. This is then used to obtain a histogram distribution for a different axial mesh.
SQPIN takes a 3-D pinwise distribution in square geometry and transforms it into a radial, (r,theta), (r,z) or (r,theta,z) distribution.
FISPEC calculates a groupwise energy spectrum from any of several different functional forms. Several components with different forms may be combined into one spectrum.
COMBI combines the space and energy distributions prepared by the other modules and presents the result in a format appropriate for the SN programs in the DOORS system.