The realmCode element

[Category: Elements]
In the CDA framework and standard, the realmCode XML element is an optional sub-element of virtually every other CDA XML element. In the underlying HL7 v3 RIM model on which CDA is based, the realmCode property is part of the "base class" from which everything is derived and the realmCode XML element is how that property is implemented.

The Realm Concept
In its standards, HL7 uses the concept of "realm" (more formally, "binding realm") to distinguish regional/geographical variances, so that the same standard can be adjusted for different regional needs.

A "realm" doesn't have to be geographical in nature - it can reflect organizational or other domains that differ in how they use a given standard and its vocabularies. Typically, however, the use of "realm" in HL7 standards is focused on accounting for regional/geographic differences.

Identification of Realm is Optional
In HL7 standards, including CDA, the explicit declaration of realm is generally optional. If a realm is not specified, the assumption is that the "universal realm" is intended and the contents are not realm-specific.

In CDA, this optional nature of "realm" usage, translates into the CDA XML schema in that the realmCode element is always an optional sub-element.

C-CDA is US Realm
Although CDA is not inherently realm-specific and can be used for any realm (i.e. geography), including the "universal realm", the C-CDA standard is US specific. As such, the US Realm Header template that every C-CDA document must adhere to, requires that the realmCode element under the ClinicalDocument root element, contain the value "US" in its code attribute.

It is not required in C-CDA that the realmCode element be used anywhere other than ClinicalDocument/realmCode (as the "realm" of the CDA Header is inherited by all contained sections and entries unless explicitly overridden). Thus, it is most common to see only one realmCode element in a C-CDA document (ClinicalDocument/realmCode), as follows:

   
   ...

realmCode XML Syntax
Refer to Codes in CDA for additional information about the XML attributes and sub-elements of CDA XML elements that represent coded concepts. In that article, refer to the section titled "Simple Codes" and note that realmCode is one of the CDA XML "simple code" elements that have only a code attribute and do not support the use of the codeSystem, displayName, or codeSystemName attributes.

It is technically permissible for multiple realmCode elements to appear side by side.

When it is used, realmCode is the first sub-element that appears (refer to Does the order of XML elements matter in CDA?, for additional information).

Other CDA PRO Know Articles Referenced In This Article

• What is CDA?


• What XML knowledge is needed for CDA work?


• What is HL7 v3?


• What is HL7?


• Does the order of XML elements matter in CDA?


• What is C-CDA?


• The US Realm Header template


• Codes in CDA