type union A
{
    B    b,
    C    c
}

type record B
{
    B8_T    iei,
    D       b_d
}

type record C
{
    B8_T    iei,
    D       c_d
}

type record D
{
    B8_T    d_f1,
    O4_T    d_f2    optional
}