The W3C  XML Security Specifications Maintenance Working Group 
has published the second edition of 
XML Signature Syntax and Processing (Second Edition) .
"This Second Edition of XML Signature Syntax and
    Processing adds Canonical XML 1.1 as a required
    canonicalization algorithm and recommends its use for inclusive
    canonicalization. This version of Canonical XML enables use of
    xml:id and xml:base Recommendations
    with XML Signature and also enables other possible future
    attributes in the XML namespace. Additional minor changes,
    including the incorporation of known errata, are documented in
    Changes in XML Signature Syntax and Processing
    (Second Edition)."