//To  find out stock in inventsum using code X++:
static void ItemOnhandSum(Args _args)
{
    InventSum           inventsum;
    Qty                 availableQty = 0;
    ;

    select sum(PostedQty),
        sum(Received),
        sum(Deducted),
        sum(Registered),
        sum(Picked),
        sum(ReservPhysical),
        sum(Ordered),
        sum(Arrived),
        sum(ReservOrdered),
        sum(OnOrder) from inventsum
        where inventsum.ItemId      == "ws-p6";
    if (inventsum)
    {
        availableQty = inventsum.PostedQty
            + inventsum.Received
            - inventsum.Deducted
            + inventsum.Registered
            - inventSum.Picked
            - inventSum.ReservPhysical
            + inventsum.Ordered
            + inventsum.Arrived
            - inventsum.ReservOrdered
            - inventsum.OnOrder;
    }
    info(strfmt('%1', availableQty));
}