System.Data.SqlClient.TdsParser.IsNull C# (CSharp) Method

        private bool IsNull(MetaType mt, ulong length)
        {
            // null bin and char types have a length of -1 to represent null
            if (mt.IsPlp)
            {
                return (TdsEnums.SQL_PLP_NULL == length);
            }

            // HOTFIX #50000415: for image/text, 0xFFFF is the length, not representing null
            if ((TdsEnums.VARNULL == length) && !mt.IsLong)
            {
                return true;
            }

            // other types have a length of 0 to represent null
            // long and non-PLP types will always return false because these types are either char or binary
            // this is expected since for long and non-plp types isnull is checked based on textptr field and not the length
            return ((TdsEnums.FIXEDNULL == length) && !mt.IsCharType && !mt.IsBinType);
        }