protected bool GetNullAttr()
{
string isNull = _r.GetAttribute(_nilID, _instanceNsID);
if (isNull == null)
isNull = _r.GetAttribute(_nullID, _instanceNsID);
if (isNull == null)
{
isNull = _r.GetAttribute(_nullID, _instanceNs2000ID);
if (isNull == null)
isNull = _r.GetAttribute(_nullID, _instanceNs1999ID);
}
if (isNull == null || !XmlConvert.ToBoolean(isNull)) return false;
return true;
}