Reference mode data is stored with a model, but you can also bring this data out of the model to be manipulated separately, or bring data from outside of the model to be used as a reference mode. To do this use the Ref Modes tab of the Model Settings dialog:
You can delete, rename, export or import using the buttons on the right. Note that if you import a .dat file you should bring in a file with the same names as model variables. Other information will not be retained with the model.