Assembly Design > Using Assembly > Working with Assemblies > About Viewing Changes to an Assembly
  
About Viewing Changes to an Assembly
You can view changes made to an assembly or assembly components in the current session. The changes are tracked against a baseline of the model as it was retrieved. Changes to components in the assembly appear with different markups in the View Changes Model Tree. Only design related changes are shown. Changes to simplified representations, environment, appearance, style, and views are not tracked.
The View Changes dialog box shows changes to the component selected before you open the dialog box. When no component is selected, it shows changes to the top-level assembly.