Schedules that have been assigned order status can have traffic instructions issued to the involved media. While traffic can be created for any schedule, only once the schedule has been converted to an order can it be emailed to media.
Traffic Instructions for each media can be specified from the Schedule Detail window for that media by clicking on the Traffic Instructions 
button.
The Traffic Summary is useful for reviewing all traffic for a particular campaign, and performing a sequential email of traffic instructions to each media. It is accessed by clicking the Traffic Summary button on the Campaign Information window.