The file is located in the modeldir folder. The file is used for the calculation of the regional parameters as a linear function of catchment descriptors. This is used when model option regestimate is set in info.txt. The file gives the group number to which each subbasin belongs. Groups are numbered 1, 2 and up. The number on the i^th row shows the group number of the i^th subbasin in the same order as in GeoData.txt (). The file has no heading, and no extra columns are allowed.