CCD ClinicalDocument.id: What is the value of root supposed to be?

You can download the CDA Release 2 documentation here: http://www.hl7.org/implement/standards/product_brief.cfm?product_id=7

Note: you will have to create an account, but not a paid account. Also, when I forgot my password, they emailed it in plain text to me. Don't use your secure password here.

In datatypes-base.xsd, you can see an explanation of II type. Root is a UID, and there are 2 types of UID. An OID and a UUID.

UUIDs are GUIDs (your example). OIDs are HL7 designated IDs. You can file for an organizational OID, and you have control over any leaf OIDs from that point. Following pattern "[0-2](\.(0|[1-9][0-9]*))*"

Between the root and extension (string), the II should be universally unique. An OID can be unique by itself. A couple examples.

OID "2.16.840.1.113883" is Hl7 (https://www.hl7.org/oid/index.cfm). Leaf ".10.20.22" is HL7 Health Story Templates. Leaf ".1.2" is a Continuity Of Care Document.

<id root="2.16.840.1.113883.10.20.22.1.2" /> is globally unique for a CCD template, extension unneeded

OID "2.16.840.1.113883.5" is HL7 V3 Code Systems. ".1" is Administrative Gender

<id root="2.16.840.1.113883.5.1" extension="M" /> is globally unique for Male

That gives you two options for generating an II for your clinical document. You can generate your own GUID. Or you can use any local identifier, if you have a meaningful ID within an OID/leaf that your organization controls. Pulling the top OID from the hl7 registry ("2.16.840.1.113883.5.3" is external users; ".1" is ProVation) as an example:

They could define leafs as needed; and each time they send a document, it would reference the same unique document. Theoretically: 100=documents; 100.2=clinical documents; extension=databaseIdentityColumn.

<id root="2.16.840.1.113883.5.3.1.100.2" extension="1" /> = first document they created
<id root="2.16.840.1.113883.5.3.1.100.2" extension="15" /> = 15th document they created

It's also perfectly valid to use OID only format, as long as it's globally unique.

<id root="2.16.840.1.113883.5.3.1.100.2.15" /> = 15th document they created

Similar to a globally unique SSN

<id root="2.16.840.1.113883.4.1" extension="111-11-1111" />

Then locally defined patient identifier could be .12=patient chart

<id root="2.16.840.1.113883.5.3.1.12" extension="ZZ1234-111111" />

Old question, I know, but I'm just learning about this stuff and I think I finally have my head wrapped around it.

The roots are basically like namespaces or domains in which the id will be valid and guaranteed to be unique. For example if your authority/organization is generating CDAs it will most likely have applied for a unique OID (the value you see in the root is an OID 2.16.840.1.113883.19.4).

So, for the example above,

    <id root="2.16.840.1.113883.19.4" extension="abc266"/>

I'm going to guess that 2.16.840.1.113883.19 is the base OID for the authority sending out the CDA and the .4 is most likely the OID to indicate that this

<id>

is in fact the document's identifier (the authority defines these OID extensions under the base OID)

"extension" is the Unique Identifier value for this particular document.

In regards to your comment about the implementation guide not having glaring errors, I've found quite the opposite in trying to figure this stuff out...there are errors abound. I do believe the root is always to be an OID, the extensions are usually UUIDs or some other unique ID.

I am working on the same thing myself. An example I received from our EHR certifying authority had the id's root looking like an OID. It was "2.16.840.1.113883.3.72".

Here is a link that may help somewhat: http://www.ihe.net/Technical_Framework/upload/ihe_lab_TF_rel2-3.pdf

I copied the relevant text below.

This element SHALL be present. It represents the unique instance identifier of the clinical document. The combination of the root and extension attributes SHALL provide a globally unique identifier. Example:

<id root="2.16.840.1.113883.19.4" extension="abc266"/>