If you wish to prevent anyone from selecting an ad spec which is already fully booked for that time frame follow these steps:
- Navigate to the Overview Tab
- Select Administration Settings
- Click on the Tab Administration Settings
- Check the box: "Disable the selection of fully booked cells"
- Hit Save
If you open the booking calendar now, the users can't select a booked item/cell and add this to their basket anymore.
You can watch the same behavior at our Extended Publication Date Calendar in the Media Configuration.