# Documentation

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## Model File Formats

The Gurobi optimizer works with a variety of file formats:

• The MPS, REW, LP, RLP, ILP, and OPB formats are used to hold optimization models.
• The MST format is used to hold MIP start data. Importing this data into a MIP model allows optimization to start with a known feasible solution.
• The HNT format is used to hold MIP hints. Importing this data into a MIP model guides the MIP search towards a guess at a high-quality feasible solution.
• The ORD format is used to hold MIP variable branching priorities. Importing this data into a MIP model affects the search strategy.
• The BAS format holds simplex basis information. Importing this data into a continuous models allows the simplex algorithm to start from the given simplex basis.
• The SOL and JSON solution formats are used to hold solution information. The latter includes additional information about the results of the optimization. Both formats can only be written after the model has been optimized.
• The ATTR format stores a collection of attributes of a model, including (multiple) MIP starts, solution, basis information, partitions, variable hints and branching priorities.
• The PRM format holds parameter values. Importing this data into a model changes the values of the referenced parameters.

Note that all of the Gurobi file I/O routines can work with compressed versions of these files. Specifically, we can read or write files with the following extensions: .zip, .gz, .bz2, and .7z (assuming that the associated compression tool, e.g., 7zip for .7z, is installed on your machine and a corresponding entry is part of you PATH environment variable).

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