4. Every Signature Property required by this specification MUST be incorporated into the signature as follows:b. A widget signature MUST include a ds:Object element within the ds:Signature element. This ds:Object element MUST have an Id attribute that is referenced by a ds:Reference element within the signature ds:SignedInfo element. Why is "Id" written in mixed case?
That's a choice that was made in the original version of the XML Signature spec 7 years ago.
