Specifies the latest quantity of the listing (or of a variation within a multi-variation listing).
For the ReviseInventoryStatus request: Specify the entire quantity that is currently available for sale. (Typically, you only pass this in when you need to update the quantity.)
ReviseInventoryStatus requires either StartPrice or Quantity (or you can specify both) for each InventoryStatus node in the request.
For the ReviseInventoryStatus response: This returns a total of the quantity available for sale plus the quantity already sold. For example, suppose the listing originally had Quantity=10, and then 8 sold. Now you restock your inventory, and you pass Quantity=10 in the ReviseInventoryStatus request. In this case, ReviseInventoryStatus returns Quantity=18 (10 available + 8 sold). To determine the quantity available, use GetItem or GetSellerList, and subtract SellingStatus.QuantitySold from Quantity. Or see QuantityAvailable in GetMyeBaySelling.
It is a good idea to maintain an adequate quantity available for fixed-price GTC listings to prevent the search rankings from dropping. Best Match search ranking is based on buyer activity, and one of the factors affecting search ranking for fixed-price listings is the recent sales score. Fixed-price items that are selling the fastest are given a relative lift in search results. Recent Sales history is tracked with a moving window to ensure it reflects the most recent activity. Due to he moving window, it is advantageous to maintain item availability (Quantity-QuantitySold) for a GTC listing.