Model file formats such as LP and MPS files are processed under the assumption that all content, including variable names and constraint names, are written using ASCII characters. Gurobi does not guarantee support for files containing non-ASCII characters, (even single-byte characters) such as "ß" and "→". Even if it works as expected in one environment, it is probably environment-dependent and may not always be interpreted as intended; therefore, such usage is not recommended.
The same applies to the Gurobi API for each programming language. It is recommended to use only ASCII characters when specifying attributes and parameters, including input/output file paths or filenames. As an example, when writing (or reading) the model file "Weiß.lp" using gurobipy's Model.write() (or gurobipy.read()) method, an error such as the following may be encountered:
gurobipy._exception.GurobiError: Unable to write to file 'Weiß.lp'gurobipy._exception.GurobiError: Unable to open file 'Weiß.lp' for input