Back order a quantity during sales order line scheduling

The following describes how to back order a quantity on an order line.

Select the Work with sales orders menu item.
Enter a new sales order or select an existing one and click Lines.
You access Work with sales orders, Order lines. Enter the Item code for the item that you want to create scheduled dispatches for. Note: If you have opened an existing sales order make certain that sales order lines for that item have not been previously entered. Select the item you want to create scheduled dispatches for and click Schedule.
You access Sales order line scheduling. Enter the following:

Schedule type: Tick the B/O radion button for back order. Note: Back order means: Compute dispatch date for one schedule line entry with today’s date and current available quantity (if available quantity is greater than zero), and one schedule line entry with earliest dispatch date and remainder of Total dispatch quantity.
Total disp quantity: Enter the total dispatch quantity.

Click OK.

Scenario
Assuming the following:

The result is:

One order line, with quantity 400, will be scheduled for the dispatch date.
One order line, with the remainder of the total dispatch quantity, (i.e. 100), will be scheduled for the earliest suggested dispatch date.