XML Signature features
  - Uses XML syntax to represent a signature over digital content (and XML
    content in particular)
 
  - Signature types:
    
      - detached: over data external to the signature document
 
      - enveloped: signature within content being signed
 
      - enveloping: content within signature being signed
 
    
   
  - Meets requirement of signing portions of documents via Transforms:
    processing the document before signing  (e.g. XPath, etc.)
 
  - Can be used to specify a signature over a list of resources (one or
    more parts of a document or different documents)