Selection Rules 
When you start the order allocation run, you must enter the Open-To-Delivery date for sales orders and stock transport orders in the respective requirement tabs of the allocation run. You can also enter a Open-To-Delivery date for future receipts in the Future Receipts tab of the allocation run. This time window depends on the date fields you have defined in the allocation type.
For example:
For a sales order, you have selected the Confirmed Delivery Date (EDATU) as the open-to delivery date in the allocation type. When you execute ARun, only those sales orders that have confirmed delivery dates within the date range of the Open-To Delivery Date (specified on the screen) are considered for allocation.
For a STO, you have selected the Confirmed Delivery Date (EINDT) as the open-to delivery date in the allocation type. When you execute ARun, only the STOs that have confirmed delivery dates within the date range of the Open-To Delivery Date (specified on the screen) are considered for allocation.
For future receipts, the Open-to-Delivery date depends on the goods receipts date defined in the allocation type. If you choose Item Delivery Date (EINDT) and execute ARun, only those receipts that have item delivery dates within the date range of the Open-To Delivery Date (specified on the screen) are considered for allocation.
For more information about Open-to-Delivery date adjustment and related example, see Dynamic Open to Delivery Date Adjustment.
Prerequisites
You have defined a stock selection rule in Customizing under 
Logistics - General 
SAP Fashion Management Order Allocation Run (ARun) Online ARun Selection Maintain Rules for Stock Selection 
. You can then assign the relevant rule in the allocation type to decide which stock can be used to cover requirements.
Features
Requirement Selection
You can decide which requirements should be selected when you execute order allocation run using the transaction ARUN. Only those articles which are ARun-relevant are considered for allocation. The types of requirements available are:
Sales orders
The sales orders are created when you enter sales documents in Sales and Distribution (SD). Only those sales orders which fulfill the following criteria are considered for allocation:
Items with ARun-relevant articles
Schedule lines with a confirmed quantity greater than zero
The delivery-related status at header and item level is complete
Stock transport orders
Only the STOs that have the SD delivery as a follow-on document and which fulfill the following criteria are considered for allocation.
Items with ARun-relevant articles from the supplying plant
Schedule lines with a committed quantity greater than zero
The shipping data is complete
Purchase-to-order
To ensure that the PTO sales orders are allocated, select the Order Allocation Required checkbox in Customizing under
Logistics - General SAP Fashion Management Order Allocation Run (ARun) Cross-Applications Shipping Maintain Order Allocation Run for Special Sales Documents .
Stock Selection Rule
The stock selection rule determines how the system selects stock elements during an order allocation run. For each stock selection rule, you must specify which stock elements that the system uses for requirements during an order allocation run. Stock elements can be of the following types:
Batch stock for articles that are batch managed
Storage location stock for articles that are not batch managed
Customer consignment stock for stock available at the customer site
Purchase-to-order (PTO) stock for a specific sales order
Future receipts that include purchase orders and shipping notifications
For physical stock, you must enter segments for each stock type and activate the corresponding stock segment to be used for allocation.