PP: XML Variable DataLength returns as 5

Hi Folks
Here is what I found, when I execute this query
set nocount on
Declare @.xmlSourceDestinationAttributes XML
Select @.xmlSourceDestinationAttributes = ''
--Select @.xmlSourceDestinationAttributes
select Datalength(@.xmlSourceDestinationAttributes)
--
5
Question
======= How come I get a value of 5 even tough I passed nothing.Try using
select CAST(@.xmlSourceDestinationAttributes AS VARBINARY(MAX))
and you will see the BOM that is at the beginning of the xml document.
Dan
> set nocount on
> Declare @.xmlSourceDestinationAttributes XML
> Select @.xmlSourceDestinationAttributes = ''
> --Select @.xmlSourceDestinationAttributes
> select Datalength(@.xmlSourceDestinationAttributes