Are you referring to World3 included in SystemDynamics library? If yes then,
Yes all the system libraries are read-only.

You should load it as normal modelica file if you want to update it not from system libraries sub-menu.
OR
You can create a new model extend it from World3 and play with some of its parameters.

Adeel.

Thanks, I'll give that a try, but am unsure how to load it as you suggest.

EDIT:  Do you mean that I would load C:\OpenModelica1.9.1Nightly\lib\omlibrary\SystemDynamics 2.1\package.mo in the connection editor, then instantiate it?  There seem to be a few missing icons and lines although it runs w/o error.  If I delete a random line I get a "too few equations" error - so maybe it's working?

(Windows7 x64, 8GB ram, i7)

So if I understand correctly, loading the SystemDynamics as a library lets one *only* instantiate and run the specific scenarios.  If one loads the above package.mo as a model, then one can instantiate the scenarios, but can also modify the various charts (e.g., Arable_Land_Dynamics, Food_Production, etc.) - *then* if one runs the scenarios, one gets different results reflecting modifications.  Is this the general OM workflow?

Thank You,
Patricia