There is 2 tables ItemSite and Location.
If you open "C:\Program Files\Microsoft Dynamics\SL\Applications\Help\Full_schema.chm" and search for ItemSite and Location you can fina a description of each field.
QtyAlloc
FLOAT (8)
Quantity on open shippers.
QtyAllocBM
FLOAT (8)
The quantity allocated (reserved) for inventory demand from Bill of Materials module transactions.
QtyAllocIN
FLOAT (8)
The quantity allocated (reserved) for inventory demand from Inventory module transactions.
QtyAllocOther
FLOAT (8)
The quantity allocated (reserved) for inventory demand from other sources. This field can be used in the future to minimize the need for schema changes. Similarly, this may be an opportunity to allow third party products to allocate inventory.
QtyAllocPORet
FLOAT (8)
The quantity allocated (reserved) for inventory demand from Purchasing Return transactions.
QtyAllocSD
FLOAT (8)
The quantity allocated (reserved) for inventory demand from Service Dispatch module transactions.
QtyAllocSO
FLOAT (8)
The quantity allocated (reserved) as a hard reservation on Sales Orders because the lot/serial numbers were specified for order type behaviors Sales Order, Invoice, and Will Call Order.
The value is the sum of SOLot.QtyShip where SOLot.Status = ‘O’pen.
Need to join back to SOSched to get the SiteID.
QtyAvail
FLOAT (8)
This field stores the quantity of the inventory that is on hand and available for sales or other uses of inventory for each item at each site.
When Customer Priority Scheduling (CPS) is set to ON in the Inventory module, then the value in this field is determined by Process Manager’s inventory planning process.
When CPS is set to OFF in the Inventory module, then the value in this field is determined according to the selected Quantity Available Supply/Demand Options on the Scheduling tab in IN Setup (10.950.00).
QtyCustOrd
FLOAT (8)
Quantity on open sales orders.
QtyInTransit
FLOAT (8)
Incoming quantity from previously-shipped 2-step transfers. The transfers originate in IN.
QtyNotAvail
FLOAT (8)
Quantity in warehouse bin locations that are marked as not available for sale.
QtyOnBO
FLOAT (8)
Quantity on back orders. This is the quantity on sales orders where the requested date is earlier than today. Quantity that appears in this bucket is also in the QtyCustOrd bucket.
QtyOnDP
FLOAT (8)
Incoming quantity from drop ship purchase orders.
QtyOnHand
FLOAT (8)
Quantity on Hand