If you want to parse or read the model formulation into memory, without solving it, choose Parse Model from the Run menu. This will let MPL read through the model file, check the syntax, and store it in memory. This is especially useful when you want to analyze the model or display a graph of the matrix.
If you have parsed the model into memory or you have solved your model once and want to solve it again, perhaps after having changed some options, you can do so by choosing Solve Current from the Run menu. This will solve the model currently in memory, without parsing the model again, which is unnecessary, if the model has not changed.
If you have changed any of the solution file options since last solver run, you can generate the solution file again without having to solve again by choosing Generate Solution from the Run menu.
When using MPL with other programs it is sometimes advantageous to know how variable names in MPL are mapped to the matrix that is sent to the solver. The mapping file contains, for each variable and constraint, the abbreviated name that is sent to the solver, the original MPL name, and all of the subscripts for vector entries. This enables the user to map the abbreviated name to the MPL name and vice versa. This file can also be automatically generated while solving by selecting Mapping File in the General Solver Options dialog box.