The data corresponding to different groups must be arranged sequentially within an input file: each group is followed by another group.

For instance, if the file is about three species, A, B and C, the individuals of A must be grouped in a submatrix A, followed by the submatrix B, followed by the submatrix C. XYOM asks not only for the input file, but also for its subdivision. In the example of three species A, B and C, a subdivision like “20,24,29” means that the 20 first rows are about individuals of species A, the next 24 rows about individuals of species B, and the next 29 rows about species C.