Hot to generate number Sequence

static client server NumberSequenceReference numRefVirtualNetworkId()
{
    return NumberSeqReference::findReference(typeId2ExtendedTypeId(typeid(HRMVirtualNetworkId)));
}

    NumberSeq= NumberSeq::newGetNum(HRMVirtualNetworkParameters::numRefVirtualNetworkId(), true, true);

    if (!numberSeq)
        //checkFailed("@SYS30552");
        throw error("@SYS30552");

    if (HRMVirtualNetworkParameters::numRefVirtualNetworkId())
    {
        HRMVirtualNetworkTable.ReferenceType        = _refenceType;
        HRMVirtualNetworkTable.Reference            = _reference;
        HRMVirtualNetworkTable.HrmVirtualNetworkId  = numberSeq.num();

        if (HRMVirtualNetworkTable.validateWrite())
        {
            HRMVirtualNetworkTable.insert();
            numberSeq.used();
        }
        else
        {
            //checkFailed("@SYS30553");
            numberSeq.abort();
            throw error("@SYS30553");
        }
    }
    else
    {
        //checkFailed("@SYS30552");
        numberSeq.abort();
        throw error("@SYS30552");
    }