Can you please provide more details on your question?
Maybe this will help:
A corridor design stage adjusts things in the view such as interval drop multiplier and what features are shown in the graphical view for the corridor.
Here is a video explaining design stage:
Here is another video that talks about design stage at around the 11:10 mark:
Here is a link that explains how to access the design stage settings that come with the examples workspace:
Here is a link explaining how to setup your own design stages: