It must be a User-type variable. If you have the Connect parameter set to Yes, this is all you need to do. If you set that to No, then you use the variable on the Connect step that you add within the Selected branch.
I thought that, but the example
icd.aef script that installs with CCX has Connect set but still has a value in
Yes, it's a required parameter. You may not have any other use for the variable in real life unless you're doing something fancy.