The optimizer can create a number of .dat files. You can load these files using Dat2vdf. To graph the results, however, you will need to load a different model, since Vensim can not graph constants.
If you specify the variables you want plotted in a Custom Graph Definition file and load this using the Graph Control in the Control Panel, then you can plot the different parameters and payoffs. You can also do various xy plots that might be useful.
Another alternative is to select Model>Import Dataset… and import the output files, then load the resulting .vdf file as a model. To do this specify the full name, including the .vdf (for example, startpoint.vdf) in the load command.
The .tab files that are created can be viewed as text files, and also can be loaded into most spreadsheet programs for further manipulation. For the most part, these files are set up so that they make sense when interpreted as a spreadsheet.
