Originally Posted by go skers

It's not really an interpretation. You don't have to proffer for standby shifts the same way you don't have to proffer for open flights. Some do for a later sign in time while others might proffer for S1 thinking they'll potentially get done earlier. CS can and will try to assign them during the proffering window but if pilots don't confirm or bid them they will default to either a RAP1 or get called at midnight for a RAP2 or an unassigned trip or standby that has ten hours of rest. If S1 or any standby for the that matter doesn't get filled it'll likely go to the junior RAP available during the 2 hour call out window.