Unlike the TDS and CWF format, when you set the Encoding Null Num property to NULLValue in XML, the value is taken as a literal. A direct comparison is done with the text string, and no logical data conversion is performed.
For example, if you set the message set property Encoding Null Num to the value NULLValue, and you set Encoding Null Num Val to 0, a FLOAT value of 0.0 or a DECIMAL value of +0 does not match NULL.
If you set Encoding Null Num to NULLEmpty, this is equivalent to setting Encoding Null Num to NULLValue and Encoding Null Num Val to "".