Toolbar Button:
Click the Options menu > Lock/Unlock Model command or the button, to toggle the model between locked and unlocked. When the model is locked, no changes that will affect the analysis results can be made until the button or command is used to unlock it.
When an analysis is run, SAFE automatically locks the model to prevent changes to the model that would invalidate the analysis results. After an analysis has been run, first unlock the model to allow changes. Note that unlocking the model deletes all of analysis results. The results are deleted because after changes have been made model, the results are no longer valid.
To save analysis results, first use the File menu > Save As command to save the file with a new name, then unlock the model with the new name and make changes to it. The original file retains the results.