title: CCD ClinicalDocument.id: What is the value of root supposed to be?
body: <p>In the CDA R2 CCD implementation guide, a <code>ClinicalDocument</code> element (the root element of the document) is supposed to have an <code>id</code> element.</p>
  
  <p>This <code>id</code> element is of the "II" datatype: <a href="http://wiki.hl7.no/index.php/R1:II" rel="noreferrer">http://wiki.hl7.no/index.php/R1:II</a>
  This states that the <code>root</code> attribute is to have an OID value, to identify the type of identification used in the <code>extension</code> attribute.</p>
  
  <p>Now, when looking at the sample CCD document that HL7 provides we see:</p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;?xml-stylesheet type="text/xsl" href="CDASchemas\cda\Schemas\CCD.xsl"?&gt;
  &lt;ClinicalDocument xmlns="urn:hl7-org:v3" xmlns:voc="urn:hl7-org:v3/voc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:hl7-org:v3 CDA.xsd" &gt;
  ...
     &lt;id root="db734647-fc99-424c-a864-7e3cda82e703"/&gt;
  ...
  &lt;/ClinicalDocument&gt;
  </code></pre>
  
  <p>The root value <strong>db734647-fc99-424c-a864-7e3cda82e703</strong> is not an OID. I'm not sure what it is, but it looks like a UUID perhaps? Anyway, is this a static value for all CCD documents, or will it differ from document to another? Why is the <code>extension</code> attribute not used, isn't that what identifies the document?</p>
  
  <p>Note that throughout that same sample document I also see things like</p>
  
  <pre><code>&lt;id root="2.16.840.1.113883.19.5" /&gt;
  </code></pre>
  
  <p>which seem to be OIDs (in the <code>root</code> attribute).</p>
  
  <p><strong>EDIT</strong>: The sample document I reference is from the HL7 CCD implementation guide, i.e it is from the official source, it is unlikely that they would have a glaring error in their sample file that nobody has noticed before.</p>