The REW format is identical to the MPS format, except in how objects are named when files are written. When writing an MPS format file, the Gurobi optimizer refers to constraints and variables using their given names. When writing an REW format file, the Gurobi optimizer ignores the given names and instead refers to the variables using a set of default names that are based on row and column numbers. Specifically, column number j gets name C000j, where the number of zeros is chosen to make the total name length at least 8 characters. Similarly, row number i gets name R000i.