The estimated annual volume is used for information purposes, or as a basis for calculating the volume value code. You can calculate the annual volume based on forecasts, and you enter it using the part's regular unit.
All Warehouses
In this field the annual volume from all warehouses are totaled. This can be useful if you purchase components centrally and the calculation of the stock levels shall be made based on all warehouses' annual volume. This applies to systems with the supplement Warehouse Management.