This table contains all Shipment Date Codes whether they are related to a Collection or they are independently working Shipment Date Codes. The two are separated by different Types.
You can use the Shipment Date Codes related to Collections via Collection Shipment Dates if your seasonal selections are represented by your Collections.
If your Collections represent a more timeless grouping of your Masters where the Shipment Date Code specifies what is included in a seasonal selection, you can let the Shipment Date Codes be the basis of your collection management.