Virtual_Fields(=[No]Automatic,[No]Computed_By)
    Novirtual_Fields

    The Virtual_Fields qualifier unloads any AUTOMATIC or COMPUTED
    BY fields as real data. This qualifier permits the transfer of
    computed values to another application. It also permits unloading
    through a view that is a union of tables or that is comprised
    of columns from multiple tables. For example, if there are two
    tables, EMPLOYEES and RETIRED_EMPLOYEES, the view ALL_EMPLOYEES
    (a union of EMPLOYEES and RETIRED_EMPLOYEES tables) can be
    unloaded.

    The Novirtual_Fields qualifier is the default, which is
    equivalent to the Virtual_Fields=[Noautomatic,Nocomputed_By)
    qualifier.

    If you specify the Virtual_Fields qualifier without a keyword,
    all fields are unloaded, including COMPUTED BY and AUTOMATIC
    table columns, and calculated VIEW columns.

    If you specify the Virtual_Fields=(Automatic,Nocomputed_By)
    qualifier or the Virtual_Fields=Nocomputed_By qualifier, data
    is only unloaded from Automatic fields. If you specify the
    Virtual_Fields=(Noautomatic,Computed_By) qualifier or the
    Virtual_Fields=Noautomatic qualifier, data is only unloaded from
    Computed_By fields.