Question about use of Id element in message header

Hi,
I was puzzled by this issue re. XML Signature. Lets
assume that I am using XML Sig to sign the header of a
message. Now, I need to <Reference> the header in the
Signature. However, I read that I cannot have a Id
element in the header. So, the URI="" (a null value)
in the Reference. 

What I wanted to check is that, is it true that I
cannot have an Id element in the header? If so, how
does one sign just the message header?

Thanks,
-Ravi


		
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