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1 CDA Overview

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2 Introduction to CDA Technical Artifacts

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3 CDA Document Exchange in HL7 Messages

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4 CDA R-MIM

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4.1 Header

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4.2 Body

4.2.1 Body Choice

The CDA body can be either an unstructured blob, or can be comprised of structured markup. Every CDA document has exactly one body, associated with the ClinicalDocument class through the component relationship.

Table X: Value set for component.typeCode (CNE)

Code	Definition
COMP (component) [default]	The associated document body is a component of the document.

4.2.1.1 NonXMLBody

The NonXMLBody class represents a document body that is in some format other than XML. NonXMLBody.text is used to reference data that is stored externally to the CDA document or to encode the data directly inline.

Rendering a referenced non-XML body requires a software tool that recognizes the particular MIME media type of the blob.

Table X: Value set for NonXMLBody.classCode (CNE)

Code	Definition
DOCBODY (document body) [default]	A context that distinguishes the body of a document from the document header.

Table X: Value set for NonXMLBody.moodCode (CNE)

Code	Definition
EVN (event) [default]	An actual occurrence of the event.

Table X: Value set for NonXMLBody.confidentialityCode (CWE)

Code *	Definition
N (normal) (codeSystem 2.16.840.1.113883.5.25)	Normal confidentiality rules (according to good health care practice) apply. That is, only authorized individuals with a legitimate medical or business need may access this item.
R (restricted) (codeSystem 2.16.840.1.113883.5.25)	Restricted access, e.g. only to providers having a current care relationship to the patient.
V (very restricted) (codeSystem 2.16.840.1.113883.5.25)	Very restricted access as declared by the Privacy Officer of the record holder.

* The codeSystem value is included here because confidentialityCode is of type CE, and therefore must carry both a code and a codeSystem.

4.2.1.2 StructuredBody

The StructuredBody class represents a CDA document body that is comprised of one or more document sections.

Table X: Value set for StructuredBody.classCode (CNE)

Code	Definition
DOCBODY (document body) [default]	A context that distinguishes the body of a document from the document header.

Table X: Value set for StructuredBody.moodCode (CNE)

Code	Definition
EVN (event) [default]	An actual occurrence of an event.

Table X: Value set for StructuredBody.confidentialityCode (CWE)

Code *	Definition
N (normal) (codeSystem 2.16.840.1.113883.5.25)	Normal confidentiality rules (according to good health care practice) apply. That is, only authorized individuals with a legitimate medical or business need may access this item.
R (restricted) (codeSystem 2.16.840.1.113883.5.25)	Restricted access, e.g. only to providers having a current care relationship to the patient.
V (very restricted) (codeSystem 2.16.840.1.113883.5.25)	Very restricted access as declared by the Privacy Officer of the record holder.

* The codeSystem value is included here because confidentialityCode is of type CE, and therefore must carry both a code and a codeSystem.

The StructuredBody class is associated with one or more Section classes through a component relationship.||

Table X: Value set for component.typeCode (CNE)

Code	Definition
COMP (component) [default]	The associated section is a component of the document body.

4.2.2 Section Attributes

Document sections can nest, can override context propagated from the header (see CDA Context, and can contain narrative and CDA entries.

An XML attribute "ID" of type XML ID, is added to Section within the CDA Schema. This attribute serves as the target of a reference (see reference). All values of attributes of type XML ID must be unique within the document (per the W3C XML specification).

Table X: Value set for Section.classCode (CNE)

Code	Definition
DOCSECT (document section) [default]	A context that subdivides the body of a document. Document sections are typically used for human navigation, to give a reader a clue as to the expected content. Document sections are used to organize and provide consistency to the contents of a document body.

Table X: Value set for Section.moodCode (CNE)

Code	Definition
EVN (event) [default]	An actual occurrence of an event.

4.2.2.1 Section.id

The unique instance identifier of a particular document section.

4.2.2.2 Section.code

The code specifying the particular kind of section (e.g. Chief Complaint, Review of Systems, Assessment). The value set is drawn from LOINC, and has a CWE coding strength.

4.2.2.3 Section.title

Represents the label of a section. If valued, it is to be rendered as part of the narrative content of the clinical document body.

4.2.2.4 Section.text

Used to store narrative to be rendered. Also referred to as the CDA Narrative Block. See Section Narrative Block for details.

4.2.2.5 Section.confidentialityCode

A value for Section.confidentialityCode overrides the value propagated from StructuredBody. See CDA Context for more details.

Table X: Value set for Section.confidentialityCode (CWE)

Code*	Definition
N (normal) (codeSystem 2.16.840.1.113883.5.25)	Normal confidentiality rules (according to good health care practice) apply. That is, only authorized individuals with a legitimate medical or business need may access this item.
R (restricted) (codeSystem 2.16.840.1.113883.5.25)	Restricted access, e.g. only to providers having a current care relationship to the patient.
V (very restricted) (codeSystem 2.16.840.1.113883.5.25)	Very restricted access as declared by the Privacy Officer of the record holder.

* The codeSystem value is included here because confidentialityCode is of type CE, and therefore must carry both a code and a codeSystem.

4.2.2.6 Section.languageCode

Specifies the human language of character data (whether they be in contents or attribute values). The values of the attribute are language identifiers as defined by the IETF (Internet Engineering Task Force) RFC 3066: Tags for the Identification of Languages, ed. H. Alvestrand. 1995 , which obsoletes RFC 1766. The HL7 code system for these values is "2.16.840.1.113883.6.121".

A value for Section.languageCode overrides the value propagated from StructuredBody. See CDA Context for more details.

4.2.3 Section Participants

4.2.3.1 author

The author participant (described above, see author), can be ascribed to a CDA section, where it overrides the value(s) propagated from the CDA header.

4.2.3.2 informant

The informant participant (described above, see informant), can be ascribed to a CDA section where it overrides the value(s) propagated from the CDA header.

4.2.3.3 subject

The subject participant represents the primary target of the entries recorded in the document. Most of the time the subject is the same as the recordTarget (see recordTarget), but need not be, for instance when the subject is a fetus observed in an obstetrical ultrasound.

The subject participant can be ascribed to a CDA section or a CDA entry. It propagates to nested components, unless overridden. The subject of a document is presumed to be the patient.

A subject is a person playing one of several possible roles (RelatedSubject class). The entity playing the role is a person (SubjectPerson class).

Table X: Value set for subject.typeCode (CNE)

Code	Definition
SBJ (subject) [default]	The principle target that the service acts on.

Table X: Value set for subject.contextControlCode (CNE)

Code	Definition
OP (overriding propagating) [default]	The participant overrides associations with the same typeCode. This overriding association will propagate to any descendant Acts reached by conducting ActRelationships. (See section "CDA Context" below.)

Table X: Value set for RelatedSubject.classCode (CNE)

Code	Definition
PRS (personal relationship) [default]	The subject has a personal relationship to the patient. The type of personal relationship is stated in SubjectRole.code, with a value drawn from the extensible (CWE) PersonalRelationshipRoleType vocabulary domain. The scoper is always the patient, and is implied.
PAT (patient)	The subject of an entry is the patient, who is identified in the recordTarget participant in the CDA header.

Table X: Value set for SubjectPerson.classCode (CNE)

Code	Definition
PSN (person) [default]	A living subject of the species homo sapiens.

Table X: Value set for SubjectPerson.determinerCode (CNE)

Code	Definition
INSTANCE (instance) [default]	The INSTANCE determiner indicates an actual occurrence of an entity, as opposed to the KIND determiner, which refers to the general description of a kind of entity. For example, one can refer to a specific car (a car instance), or one can refer to cars in general (a car kind).

4.2.4 Section Relationships

4.2.4.1 component

The "component" Act Relationship is used to nest a Section within a Section. Context propagates to nested sections (see CDA Context).

Table X: Value set for component.typeCode (CNE)

Code	Definition
COMP (component) [default]	The nested section is a component of the outer section.

4.2.4.2 entry

The relationship between a section and its entries is encoded in the intervening "entry" Act Relationship.

NOTE: See Referencing in and out of the narrative block for a discussion of referencing in and out of a section's narrative block.

The narrative of each Section, together with the multimedia content referenced in the narrative, comprises the complete authenticated content of the Section. This multimedia content consists of ObservationMedia and RegionOfInterest entries referenced by tags in the Section.text. This is the only case where the entries contain authenticated content that must be rendered with the narrative.

In terms of the relationship between a section and its entries, CDA defines a default general case, and a more specific case that can be used when applicable.

The entry relationship is defaulted to "COMP" (component), for the general case where the only assertion is that the related entries are contained within the source section and no other semantics are implied. In this case, the narrative is the original authenticated content. The CDA entries are created by various techniques (e.g., natural language processing, a human coder, a structured data entry tool that outputs both entries and a text report). The method of entry creation may be indicated by the entry participants (e.g., by identifying the algorithm or person that generated them). Relationships between various entries (such as two Observations or an Observation and an ObservationMedia) are encoded using the relationship types defined in entryRelationship.

A section may also have no narrative content in the case where the entries represent information that is not part of the clinical content of the document. A report may embed information referencing evidence data, reagents, calibration or other information that may be used for later processing but is not part of the clinical content. Such entries are also linked to the Section with ActRelationships possessing typeCode="COMP".

The entry relationship "DRIV" (is derived from) can be used in the special case where the narrative is fully derived from CDA Entries. When a report consisting entirely of structured entries is transformed into CDA, the encoding application must ensure that the authenticated content (narrative plus multimedia) is a faithful and complete rendering of the clinical content of the structured source data. This ensures that the narrative plus multimedia represents, as in all CDA documents, the complete authenticated content of the Section. In this case, narrative plus multimedia does not contain any clinical content that is not present in the Entries. An example of this case is a DICOM Structured Reporting document of obstetrical measurements made by ultrasound, rendered into a tabular report by a program converting it to CDA narrative block. If the typeCode of the ActRelationship linking these Entries to the Section was "DRIV", it would indicate to a receiving application: 1) the source of the narrative block is the Entries; 2) the contents of the two are equivalent.

The entries sourced from a Section may have a mix of ActRelationship typeCodes. In such a case, the union of the targets with a "DRIV" relationship are those used to generate the narrative block, and are those that, taken in total, are equivalent to the narrative block. Additional entries with "COMP" relationships are contained within the same section, with no implied semantics.

Table X: Value set for entry.typeCode (CNE)

Code	Definition
COMP (component) [default]	The associated entry is a component of the section. No semantic relationship is implied.
DRIV (is derived from)	The narrative was rendered from the CDA Entries, and contains no clinical content not derived from the entries.

4.2.5 Section Narrative Block

The Section.text field is used to store narrative to be rendered, as described above in CDA Conformance, and is therefore referred to as the CDA Narrative Block.

The CDA Narrative Block schema can be found here.

The content model of the CDA Narrative Block schema is specially hand crafted to meet the requirements outlined above (see Human Readability and Rendering CDA Documents). The schema is registered as a MIME type (text/x-hl7-text+xml), which is the fixed media type for Section.text. Components of the schema are described in the sections that follow.

4.2.5.1 <content>

The CDA <content> element is used to wrap a string of text so that it can be explicitly referenced, or so that it can suggest rendering characteristics. The <content> element can nest recursively, which enables wrapping a string of plain text down to as small a chunk as desired.

The <content> element contains an optional identifier, that can serve as the target of a reference. All values of attributes of type XML ID must be unique within the document (per the W3C XML specification). The originalText component of a RIM attribute present in any CDA entry can make explicit reference to the identifier, thereby indicating the original text associated with the attribute in the CDA entry.

Note: The <content> element is not the only element which can serve as the target of a reference. All narrative elements (including <text>) contain an ID element which can be referenced by the originalText component in a CDA entry. <content> is simply a tool which can be used to reference only a portion of a longer string contained in another narrative element.

Example X

<section>
   <code code="10153-2" 
    codeSystem="2.16.840.1.113883.6.1" 
    codeSystemName="LOINC"/>
   <title>Past Medical History</title>
   <text>
    There is a history of <content ID="a1">Asthma</content>
   </text>
   <entry>
      <observation classCode="OBS" moodCode="EVN">
         <code code="195967001" 
          codeSystem="2.16.840.1.113883.6.96" 
          codeSystemName="SNOMED CT" 
          displayName="Asthma">
            <originalText>
               <reference value="#a1"/>
            </originalText>
         </code>
         <statusCode code="completed"/>
      </observation>
   </entry>
</section>

There is no requirement that CDA entries must reference into the CDA Narrative Block. The referencing mechanism can be used where it is important to represent the original text component of a coded CDA entry.

The <content> element contains an optional "revised" attribute that can be valued with "insert" or "delete", which can be used to indicate narrative changes from the last version of a CDA document. The attribute is limited to a single generation, in that it only reflects the changes from the preceding version of a document. If applied, it needs to be used in conjunction with standard CDA revision tracking. Changes to a CDA document that has been released for patient care still require a formal versioning and revision, and the revised document can optionally carry the "revised" attribute to show the delta in the narrative. Receivers are required to interpret the "revised" attribute when rendering by visually distinguishing or suppressing deleted narrative.

4.2.5.2 <linkHtml>

The CDA <linkHtml> is a generic referencing mechanism, similar, but not identical, to the HTML anchor tag. It can be used to reference identifiers that are either internal or external to the document.

Multimedia that is integral to a document, and part of the attestable content of the document requires the use of the ObservationMedia CDA entry, which is referenced by the <renderMultiMedia> element (see <renderMultiMedia>). Multimedia that is simply referenced by the document and not an integral part of the document can use <linkHtml>.

The source of a link uses the linkHtml.href attribute. The target of an internal reference is an identifier of type XML ID, which can exist on other elements in the same or a different narrative block, or XML ID attributes that have been added to the <section>, <ObservationMedia>, or <renderMultiMedia> elements of the CDA Schema. The linkHtml.name attribute is deprecated, because attributes of type XML ID provide an alternative and more consistent target for referencing. Following the conventions of HTML, an internal link is prefaced with the pound sign, as shown in the following example.

Example X

<section ID="SECT001">
   <code code="10164-2" codeSystem="2.16.840.1.113883.6.1" 
    codeSystemName="LOINC"/>
   <title>History of Present Illness</title>
   <text>Mr. Smith is a 57 year old male presenting with 
    chest pain. He sustained a myocardial infarction 3 years 
    ago, ...
   </text>
</section>

 ...

<section ID="SECT003">
   <code code="10153-2" codeSystem="2.16.840.1.113883.6.1" 
    codeSystemName="LOINC"/>
   <title>Past Medical History</title>
   <text>History of coronary artery disease, as noted
    <linkHtml href="#SECT001">above</linkHtml>.</text>
</section>

CDA links do not convey shareable meaning. Shareable semantics are only achieved by the inclusion of CDA entries and their associated formalized relationships. There is no requirement that a receiver render an internal or external link, or the target of an external link.

4.2.5.3 <sub> and <sup>

The CDA <sub> and <sup> elements are used to indicate subscripts and superscripts, respectively.

Receivers are required to interpret these elements when rendering by visually distinguishing subscripted and superscripted characters.

4.2.5.4 <br>

The CDA <br/> element is used to indicate a hard line break. It differs from the CDA <paragraph> element in that the <br/> element has no content. Receivers are required to interpret this element when rendering so as to represent a line break.

4.2.5.5 <footnote> and <footnoteRef>

The CDA <footnote> element is used to indicate a footnote. The element contains the footnote, inline with the flow of text to which it is applied.

The <footnoteRef> element can reference an existing footnote in the same or different CDA Narrative Block of the same document. It can be used when the same footnote is being used multiple times. The value of the footnoteRef.IDREF must be an footnote.ID value in the same document.

Receivers are required to interpret these elements when rendering by visually distinguishing footnoted text. The exact rendition is at the discretion of the recipient, and might include a mark at the location of the footnote with a hyperlink to the footnoted text, a simple demarcation (such as "This is the text [this is the footnote] that is being footnoted"), etc.

4.2.5.6 <renderMultiMedia>

The CDA <renderMultiMedia> element references external multimedia that is integral to a document, and part of the attestable content of the document, and serves to show where the referenced multimedia is to be rendered.

The <renderMultiMedia> element has an optional , and contains a required referencedObject attribute (of type XML IDREFS), the values of which must equal the XML ID value(s) of ObservationMedia or RegionOfInterest CDA entries within the same document.

Example X

<section>
   <code code="8709-8" codeSystem="2.16.840.1.113883.6.1" 
    codeSystemName="LOINC"/>
   <title>Skin exam</title>
   <text>Erythematous rash, palmar surface, left index 
    finger.<renderMultiMedia referencedObject="MM1"/>
   </text>
   <entry>
      <observationMedia classCode="OBS" moodCode="EVN" ID="MM1">
         <id root="2.16.840.1.113883.19.2.1"/>
         <value xsi:type="ED" mediaType="image/jpeg">
            <reference value="left_hand_image.jpeg"/>
         </value>
      </observationMedia>
   </entry>
</section>

Multimedia that is simply referenced by the document and not an integral part of the document must use <linkHtml>.

The expected behavior is that the referenced multimedia should be rendered or referenced at the point of reference. Where a caption is present, it must also be rendered. <renderMultiMedia> can either reference a single ObservationMedia, or one or more RegionOfInterest. If <renderMultiMedia> references a single ObservationMedia, that ObservationMedia should be rendered or referenced at the point of reference. If <renderMultiMedia> references one or more RegionOfInterest, all RegionOfInterests should be rendered or referenced at the point of reference, atop the multimedia they are regions of. If <renderMultiMedia> references more than one RegionOfInterest, each RegionOfInterest must be a region on the same multimedia.

4.2.5.7 <paragraph>

A CDA <paragraph> is similar to the HTML paragraph, which allows blocks of narrative to be broken up into logically consistent structures. A CDA <paragraph> element contains an optional caption, which if present must come first before any other character data.

4.2.5.8 <list>

A CDA <list> is similar to the HTML list. A CDA <list> has an optional caption, and contains one or more <item> elements. A CDA <item> element contains an optional caption, which if present must come first before any other character data. The required listType attribute specifies whether the <list> is ordered or unordered (with unordered being the default). Unordered lists are typically rendered with bullets, whereas ordered lists are typically rendered with numbers, although this is not a requirement.

4.2.5.9 <table>

The CDA <table> is similar to the HTML table. The table markup is for presentation purposes only and, unlike a database table, does not possess meaningful field names. Remember to access the discrete data conveyed in a CDA document, process the RIM models contained within the <entry> element.

CDA modifies the strict XHTML table model by removing formatting tags and by setting the content model of cells to be similar to the contents of other elements in the CDA Narrative Block. A notable enhancement to the CDA R2.1 standard is the support of the <table> element within <td> & <th> elements. The support of tables within tables was not supported in CDA R2.0, but has been added for those implementation requiring complex table layouts.

The table.border, table.cellspacing, and table.cellpadding attributes are deprecated, because the styleCode attribute (see styleCode attribute) provides a more consistent way for senders to suggest rendering characteristics.

4.2.5.10 <caption>

The CDA <caption> is a label for a paragraph, list, list item, table, or table cell. It can also be used within the <renderMultiMedia> element to indicate a label for referenced ObservationMedia and RegionOfInterest entries. A <caption> contains plain text and may contain links and footnotes.

4.2.5.11 styleCode attribute

The styleCode attribute is used within the CDA Narrative Block to give the instance author the ability to suggest rendering characteristics of the nested character data. Receivers are not required to render documents using the style hints provided and can present stylized text in accordance with their local style conventions.

The value set is drawn from the HL7 styleType vocabulary domain, and has a CWE coding strength.

Table X: Value set for styleCode (CWE)

Code	Definition
Font style (Defines font rendering characteristics.)
Bold	Render with a bold font.
Underline	Render with an underlines font.
Italics	Render italicized.
Emphasis	Render with some type of emphasis.
Table rule style (Defines table cell rendering characteristics.
Lrule	Render cell with left-sided rule.
Rrule	Render cell with right-sided rule.
Toprule	Render cell with rule on top.
Botrule	Render cell with rule on bottom.
Ordered list style (Defines rendering characteristics for ordered lists.)
Arabic	List is ordered using Arabic numerals: 1, 2, 3.
LittleRoman	List is ordered using little Roman numerals: i, ii, iii.
BigRoman	List is ordered using big Roman numerals: I, II, III.
LittleAlpha	List is ordered using little alpha characters: a, b, c.
BigAlpha	List is ordered using big alpha characters: A, B, C.
Unordered list style (Defines rendering characteristics for unordered lists.)
Disc	List bullets are simple solid discs.
Circle	List bullets are hollow discs.
Square	List bullets are solid squares.

Local extensions to the styleType vocabulary domain must follow the following convention: [x][A-Za-z][A-Za-z0-9]* (first character is "x", second character is an upper or lower case A-Z, remaining characters are any combination of upper and lower case letters or numbers).

The styleCode attribute can contain multiple values, separated by white space. Where an element containing a styleCode attribute is nested within another element containing a styleCode attribute, the style effects are additive, as in the following example:

Example X

<section>
   <text><content styleCode="Bold">This is rendered bold, 
    <content styleCode="Italics">this is rendered bold and 
    italicized,</content> this is rendered bold. </content>
    <content styleCode="Bold Italics">This is also rendered 
    bold and italicized.</content>
   </text>
</section>

4.2.5.12 Referencing in and out of the narrative block

NOTE: See entry for a discussion of the relationships between a section and its contained entries.

To summarize the mechanisms for referencing in and out of the CDA Narrative Block:

CDA entries can point in to the <content> element of the CDA Narrative Block (see <content>).

The <linkHtml> element of the CDA Narrative Block can reference targets that are either internal or external to the document (see <linkHtml>).

The <footnoteRef> element of the CDA Narrative Block can reference a <footnote> element in the same or different CDA Narrative Block of the same document (see <footnote> and <footnoteRef>).

The <renderMultiMedia> element of the CDA Narrative Block can point out to CDA ObservationMedia and RegionOfInterest entries of the same document (see <renderMultiMedia>).

4.2.6 Entry Acts

CDA entries represent the structured computer-processable components within a document section. Each section can contain zero to many entries.

Clinical documents contain a wide breadth of content, requiring much of the RIM to enable a full and complete encoding. The current set of CDA entries have been developed in response to identified requirements and scenarios that are in CDA's scope. Rather than creating specific entries for each scenario, similar requirements are merged to create broader entries, which can then be constrained within a particular realm or implementation. This approach is consistent with the approach taken by CEN, DICOM, and OpenEHR.

The model for CDA entries is derived from the shared HL7 Clinical Statement model, which is a collaborative project between several committees striving to provide a consistent representation of clinical observations and acts across various V3 specifications.

4.2.6.1 Act

A derivative of the RIM Act class, to be used when the other more specific classes aren't appropriate.

Act.negationInd, when set to "true", is a positive assertion that the Act as a whole is negated. Some properties such as Act.id, Act.moodCode, and the participations are not affected. These properties always have the same meaning: i.e., the author remains the author of the negative Act. An act statement with negationInd is still a statement about the specific fact described by the Act. For instance, a negated "finding of wheezing on July 1" means that the author positively denies that there was wheezing on July 1, and that he takes the same responsibility for such statement and the same requirement to have evidence for such statement than if he had not used negation.

Table X: Value set for Act.classCode (CNE)

Code	Definition
ACT (act)	A healthcare service.
ACCM (accommodation)	An accommodation is a service provided for a Person or other LivingSubject in which a place is provided for the subject to reside for a period of time.
CONS (consent)	Represents informed consents and other medico-legal transactions between the patient (or legal guardian) and the provider.
CTTEVENT (clinical trial timepoint event)	An identified point during a clinical trial at which one or more actions are scheduled to be performed (definition mood), or are actually performed (event mood).
INC (incident)	An event that occurred outside of the control of one or more of the parties involved. Includes the concept of an accident.
INFRM (inform)	The act of transmitting information and understanding about a topic (or requesting that such information be transmitted) to a subject.
PCPR (care provision)	A patient care provision is the taking on of the responsibility by a performer for the health care of a patient or group of patients.
REG (registration)	Represents the act of maintaining information about an entity or role in a registry.
SPCTRT (specimen treatment)	A procedure or treatment performed on a specimen to prepare it for analysis

Table X: Value set for Act.moodCode (CNE)

Code	Definition
EVN (event)	The entry defines an actual occurrence of an event.
INT (intent)	The entry is intended or planned.
APT (appointment)	The entry is planned for a specific time and place.
ARQ (appointment request)	The entry is a request for the booking of an appointment.
PRMS (promise)	A commitment to perform the stated entry.
PRP (proposal)	A proposal that the stated entry be performed.
RQO (request)	A request or order to perform the stated entry.
DEF (definition)	The entry defines a service (master).

4.2.6.2 Encounter

A derivative of the RIM PatientEncounter class, used to represent related encounters, such as follow-up visits or referenced past encounters.

NOTE: The EncompassingEncounter class in the CDA Header (see Header Relationships) represents the setting of the clinical encounter during which the documented act occurred. The Encounter class in the CDA Body is used to represent other related encounters.

Table X: Value set for Encounter.classCode (CNE)

Code	Definition
ENC (encounter)	An interaction between a patient and healthcare participant(s) for the purpose of providing patient service(s) or assessing the health status of a patient.

Table X: Value set for Encounter.moodCode (CNE)

Code	Definition
INT (intent)	The entry is intended or planned.
EVN (event)	The entry defines an actual occurrence of an event.
APT (appointment)	The entry is planned for a specific time and place.
ARQ (appointment request)	The entry is a request for the booking of an appointment.
PRMS (promise)	A commitment to perform the stated entry.
PRP (proposal)	A proposal that the stated entry be performed.
RQO (request)	A request or order to perform the stated entry.

4.2.6.3 Observation

A derivative of the Observation(§ RIM 5.36) class, it is intended to result in new information about a subject. The main difference between Observations and other Acts is that Observations have a value attribute. The code attribute of Observation and the value attribute of Observation must be considered in combination to determine the semantics of the observation.

Table X: Observation Attributes

Attribute	Data Type	Cardinality	Value Set Binding	Binding Type
classCode	CS	[1..1]	OBS	CLOSED
moodCode	CS	[1..1]	V:x_ActMoodDocumentObservation	CLOSED
id	SET <II>	[0..*]
code	CD	[1..1]	D:ObservationType	OPEN
actonNegationInd	BL	[0..1]
negationInd (Deprecated)	BL	[0..1]
derivationExpr	ST	[0..1]
title	ED	[0..1]
text	ED	[0..1]
statusCode	CS	[0..1]	V:ActStatus	CLOSED
effectiveTime	IVL<TS>	[0..1]
activityTime	GTS	[0..1]
availabilityTime	TS	[0..1]
priorityCode	CE	[0..1]	D:ActPriority	OPEN
confidentialityCode	SET<CE>	[0..*]	D:Confidentiality	OPEN
repeatNumber	IVL<INT>	[0..1]
uncertaintyCode	CE	[0..1]	D:ActUncertainty	OPEN
languageCode	CE	[0..1]	D:HumanLanguage	CLOSED
isCriterionInd	BL	[0..1]
value	SET<ANY>	[0..*]	D:ObservationValue	OPEN
valueNegationInd	BL	[0..1]
interpretationCode	SET<CE>	[0..*]	D:ObservationInterpretation	OPEN
methodCode	SET<CE>	[0..*]	D:ObservationMethod	OPEN
targetSiteCode	SET<CD>	[0..*]	D:ActSite	OPEN

Observation Negation

Observation.actionNegationInd, indicates that the Act statement is a negation of the Act in Event mood as described by the descriptive attributes. For Observations, actionNegationInd indicates that the act itself did not occur. I.e. no observation took place. To indicate that an observation did occur but the finding was negative, use Observation.valueNegationInd.

Observation.valueNegationInd, indicates that when the observation event occurred, the finding communicated by the value attribute was NOT found. So, when we want to indicate the patient does not have asthma, we can negate a finding of asthma, using this indicator. Note: This attribute should only be used when the terminology used for Observation.value is not itself capable of expressing negated findings. (E.g. ICD9).

Observation.negationInd, is deprecated in CDA R2.1, and is only retained for backwards compatibility. It was deprecated as the type of negation required knowledge of template documentation, I.e. value or action negation. It was used in CDA R2.0 to indicate that the Act statement is a negation of the Act as described by the descriptive attributes.

Table X: Value set for Observation.classCode (CLOSED)

Code	Print Name	Definition
OBS	Observation	An act that is intended to result in new information about a subject. The main difference between Observations and other Acts is that Observations have a value attribute. The code attribute of Observation and the value attribute of Observation must be considered in combination to determine the semantics of the observation.
Any OBS subtype		See vocabulary domain(s) "v:ActClassObservation","v:ActClassCompositeOrder","v:ActClassProcessStep" for allowable values.

Table X: Value set for Observation.moodCode (CLOSED)

Code	Print Name	Definition
APT	appointment	A planned Act for a specific time and place.
ARQ	appointment request	A request for the booking of an appointment.
EVN	event	A service that actually happens, may be an ongoing service or a documentation of a past service.
DEF	definition	A definition of a service (master).
GOL	goal	An observation that is considered to be desirable to occur in the future. The essential feature of a goal is that if it occurs it would be considered as a marker of a positive outcome or of progress towards a positive outcome.
INT	intent	An intention or plan to perform a service. Historical note: in previous RIM versions, the intent mood was captured as a separate class hierarchy, called Service_intent_or_order.
PRMS	promise	An intent to perform a service that has the strength of a commitment, i.e., other parties may rely on the originator of such promise that said originator will see to it that the promised act will be fulfilled. A promise can be either solicited or unsolicited.
PRP	proposal	A non-mandated intent to perform an act. Used to record intents that are explicitly not Orders. Professional responsibility for the 'proposal' may or may not be present.
RSK	risk	An act that may occur in the future and which is regarded as undesirable. The essential feature of a risk is that if it occurs this would be regarded as a marker of a negative outcome or of deterioration towards a negative outcome. Recording a risk indicates that it is seen as more likely to occur in the subject than in a general member of the population but does not mean it is expected to occur.
RQO	request	A request or order for a service is an intent directed from a placer (request author) to a fulfiller (service performer).

|An Observation can have zero to many referenceRange relationships, which relate an Observation to the ObservationRange class, where the expected range of values for a particular observation can be specified.

Table X: Value set for referenceRange.typeCode (CLOSED)

Code	Print Name	Definition
REFV	has reference values [default]	Reference ranges are essentially descriptors of a class of result values assumed to be "normal", "abnormal", or "critical." Those can vary by sex, age, or any other criterion. Source and target are observations, the target is in criterion mood. This link type can act as a trigger in case of alarms being triggered by critical results.

Table X: Value set for ObservationRange.classCode (CLOSED)

Code	Print Name	Definition
OBS	Observation	An act that is intended to result in new information about a subject. The main difference between Observations and other Acts is that Observations have a value attribute. The code attribute of Observation and the value attribute of Observation must be considered in combination to determine the semantics of the observation.
Any OBS subtype		See vocabulary domain(s) "v:ActClassObservation","v:ActClassCompositeOrder","v:ActClassProcessStep" for allowable values.

Table X: Value set for ObservationRange.moodCode (CLOSED)

Code	Print Name	Definition
EVN.CRT	event criterion [default]	A criterion or condition over service events that must apply for an associated service to be considered.

4.2.6.4 ObservationMedia

A derivative of the RIM Observation class that represents multimedia that is logically part of the current document. This class is only for multimedia that is logically part of the attested content of the document. Rendering a referenced ObservationMedia requires a software tool that recognizes the particular MIME media type.

An XML attribute "ID" of type XML ID, is added to ObservationMedia within the CDA Schema. This attribute serves as the target of a <renderMultiMedia> reference (see <renderMultiMedia>). All values of attributes of type XML ID must be unique within the document (per the W3C XML specification).

The distinction between ObservationMedia and ExternalObservation is that ObservationMedia entries are part of the attested content of the document whereas ExternalObservations are not. For instance, when a clinician draws a picture as part of a progress note, that picture is represented as a CDA ObservationMedia. If that clinician is also describing a finding seen on a chest-x-ray, the referenced chest-x-ray is represented as a CDA ExternalObservation.

Table X: Value set for ObservationMedia.classCode (CNE)

Code	Definition
OBS (observation)	A multimedia observation.

Table X: Value set for ObservationMedia.moodCode (CNE)

Code	Definition
EVN (event)	The entry defines an actual occurrence of an event.

4.2.6.5 Organizer

A derivative of the RIM Act class, which can be used to create arbitrary groupings of other CDA entries that share a common context. An Organizer can contain other Organizers and/or other CDA entries, by traversing the component relationship. An Organizer can refer to external acts by traversing the reference relationship. An Organizer cannot be the source of an entryRelationship relationship.

NOTE: CDA entries such as Observation can also contain other CDA entries by traversing the entryRelationship class. There is no requirement that the Organizer entry be used in order to group CDA entries.

Table X: Value set for Organizer.classCode (CNE)

Code	Definition
BATTERY (battery)	A battery specifies a set of observations. These observations typically have a logical or practical grouping for generally accepted clinical or functional purposes, such as observations that are grouped together because of automation.
CLUSTER (cluster)	A group of entries that have a logical association with one another. The Cluster class permits aggregation into a compound statement.

Table X: Value set for Organizer.moodCode (CNE)

Code	Definition
EVN (event)	The entry defines an actual occurrence of an event

4.2.6.6 Procedure

A derivative of the RIM Procedure class, used for representing procedures.

Procedure.negationInd, when set to "true", is a positive assertion that the Procedure as a whole is negated. Some properties such as Procedure.id, Procedure.moodCode, and the participations are not affected. These properties always have the same meaning: i.e., the author remains the author of the negative Procedure. A procedure statement with negationInd is still a statement about the specific fact described by the Procedure. For instance, a negated "appendectomy performed" means that the author positively denies that there was ever an appendectomy performed, and that he takes the same responsibility for such statement and the same requirement to have evidence for such statement than if he had not used negation.

Table X: Value set for Procedure.classCode (CNE)

Code	Definition
PROC (procedure)	An act whose immediate and primary outcome (post-condition) is the alteration of the physical condition of the subject.

Table X: Value set for Procedure.moodCode (CNE)

Code	Definition
EVN (event)	The entry defines an actual occurrence of an event.
INT (intent)	The entry is intended or planned.
APT (appointment)	The entry is planned for a specific time and place.
ARQ (appointment request)	The entry is a request for the booking of an appointment.
PRMS (promise)	A commitment to perform the stated entry.
PRP (proposal)	A proposal that the stated entry be performed.
RQO (request)	A request or order to perform the stated entry.
DEF (definition)	The entry defines a service (master).

4.2.6.7 RegionOfInterest

A derivative of the RIM Observation class that represents a region of interest on an image, using an overlay shape. RegionOfInterest is used to make reference to specific regions in images, e.g., to specify the site of a physical finding by "circling" a region in a schematic picture of a human body. The units of the coordinate values in RegionOfInterest.value are in pixels, expressed as a list of integers. The origin is in the upper left hand corner, with positive X values going to the right and positive Y values going down. The relationship between a RegionOfInterest and its referenced ObservationMedia or ExternalObservation is specified by traversing the entryRelationship or reference class, respectively, where typeCode equals "SUBJ". A RegionOfInterest must reference exactly one ObservationMedia or one ExternalObservation. If the RegionOfInterest is the target of a <renderMultimedia> reference, then it shall only reference an ObservationMedia and not an ExternalObservation.

An XML attribute "ID" of type XML ID, is added to RegionOfInterest within the CDA Schema. This attribute serves as the target of a <renderMultiMedia> reference (see <renderMultiMedia>). All values of attributes of type XML ID must be unique within the document (per the W3C XML specification).

Table X: Value set for RegionOfInterest.classCode (CNE)

Code	Definition
ROIOVL (overlay region of interest)	A Region of Interest specified for an image using an overlay shape.

Table X: Value set for RegionOfInterest.moodCode (CNE)

Code	Definition
EVN (event)	The entry defines an actual occurrence of an event.

Table X: Value set for RegionOfInterest.code (CNE)

Code	Definition
CIRCLE (circle)	A circle defined by two (column,row) pairs. The first point is the center of the circle and the second point is a point on the perimeter of the circle.
ELLIPSE (ellipse)	An ellipse defined by four (column,row) pairs, the first two points specifying the endpoints of the major axis and the second two points specifying the endpoints of the minor axis.
POINT (point)	A single point denoted by a single (column,row) pair, or multiple points each denoted by a (column,row) pair.
POLY (polyline)	A series of connected line segments with ordered vertices denoted by (column,row) pairs; if the first and last vertices are the same, it is a closed polygon.

The following example illustrates one sample use of RegionOfInterest. In this case, the clinician has identified a rash upon physical examination of the skin, and indicates this by creating a region of interest atop a hand image taken from an image library. The narrative block references the RegionOfInterest via the <renderMultiMedia> tag, and the referenced RegionOfInterest references the hand image.

Example X

<section>
   <code code="8709-8" codeSystem="2.16.840.1.113883.6.1" 
    codeSystemName="LOINC"/>
   <title>Skin Exam</title>
   <text>Erythematous rash, palmar surface, left index 
    finger.<renderMultiMedia referencedObject="MM2"/>
   </text>
   <entry>
      <observation classCode="OBS" moodCode="EVN">
         <code code="271807003" 
          codeSystem="2.16.840.1.113883.6.96" 
          codeSystemName="SNOMED CT" 
          displayName="Rash"/>
         <statusCode code="completed"/>
         <targetSiteCode code="48856004" 
          codeSystem="2.16.840.1.113883.6.96" 
          codeSystemName="SNOMED CT" 
          displayName="Skin of palmer surface of index finger">
            <qualifier>
               <name code="78615007" 
                codeSystem="2.16.840.1.113883.6.96" 
                displayName="with laterality"/>
               <value code="7771000" 
                codeSystem="2.16.840.1.113883.6.96" 
                displayName="left"/>
            </qualifier>
         </targetSiteCode>
         <entryRelationship typeCode="SPRT">
            <regionOfInterest classCode="ROIOVL" moodCode="EVN" ID="MM2">
               <id root="2.16.840.1.113883.19.3.1"/>
               <code code="ELLIPSE"/>
               <value value="3"/>
               <value value="1"/>
               <value value="3"/>
               <value value="7"/>
               <value value="2"/>
               <value value="4"/>
               <value value="4"/>
               <value value="4"/>
               <entryRelationship typeCode="SUBJ">
                  <observationMedia classCode="OBS" moodCode="EVN">
                     <id root="2.16.840.1.113883.19.2.1"/>
                     <value mediaType="image/jpeg">
                        <reference value="lefthand.jpeg"/>
                     </value>
                  </observationMedia>
               </entryRelationship>
            </regionOfInterest>
         </entryRelationship>
      </observation>
   </entry>
</section>

4.2.6.8 SubstanceAdministration

A derivative of the RIM SubstanceAdministration class, used for representing medication-related events such as medication history or planned medication administration orders.

SubstanceAdministration.negationInd, when set to "true", is a positive assertion that the SubstanceAdministration as a whole is negated. Some properties such as SubstanceAdministration.id, SubstanceAdministration.moodCode, and the participations are not affected. These properties always have the same meaning: i.e., the author remains the author of the negative SubstanceAdministration. A substance administration statement with negationInd is still a statement about the specific fact described by the SubstanceAdministration. For instance, a negated "aspirin administration" means that the author positively denies that aspirin is being administered, and that he takes the same responsibility for such statement and the same requirement to have evidence for such statement than if he had not used negation.

Table X: Value set for SubstanceAdministration.classCode (CNE)

Code	Definition
SBADM (substance administration)	The act of introducing or otherwise applying a substance to the subject.

Table X: Value set for SubstanceAdministration.moodCode (CNE)

Code	Definition
EVN (event)	The entry defines an actual occurrence of an event.
INT (intent)	The entry is intended or planned.
PRMS (promise)	A commitment to perform the stated entry.
PRP (proposal)	A proposal that the stated entry be performed.
RQO (request)	A request or order to perform the stated entry.

SubstanceAdministration.priorityCode categorizes the priority of a substance administration. SubstanceAdministration.doseQuantity indicates how much medication is given per dose. SubstanceAdministration.rateQuantity can be used to indicate the rate at which the dose is to be administered (e.g., the flow rate for intravenous infusions). SubstanceAdministration.maxDoseQuantity is used to capture the maximum dose of the medication that can be given over a stated time interval (e.g., maximum daily dose of morphine, maximum lifetime dose of doxorubicin). SubstanceAdministration.effectiveTime is used to describe the timing of administration. It is modeled using the GTS data type to accommodate various dosing scenarios, as illustrated in the following example.

Example X

<section>
   <text>Take captopril 25mg PO every 12 hours, starting on 
    Jan 01, 2002, ending on Feb 01, 2002.
   </text>
   <entry>
      <substanceAdministration classCode="SBADM" moodCode="RQO">
         <effectiveTime xsi:type="IVL_TS">
            <low value="20020101"/>
            <high value="20020201"/>
         </effectiveTime>
         <effectiveTime xsi:type="PIVL_TS" operator="A">
            <period value="12" unit="h"/>
         </effectiveTime>
         <routeCode code="PO" 
          codeSystem="2.16.840.1.113883.5.112" 
          codeSystemName="RouteOfAdministration"/>
         <doseQuantity value="1"/>
         <consumable>
            <manufacturedProduct>
               <manufacturedLabeledDrug>
                  <code code="318821008" 
                   codeSystem="2.16.840.1.113883.6.96" 
                   codeSystemName="SNOMED CT" 
                   displayName="Captopril 25mg tablet"/>
               </manufacturedLabeledDrug>
            </manufacturedProduct>
         </consumable>
      </substanceAdministration>
   </entry>
</section>

The capture of medication-related information also involves the interrelationship of SubstanceAdministration with several other classes. The consumable participation is used to bring in the LabeledDrug or Material entity that describes the administered substance. The LabeledDrug class, which is an Entity class playing the Role of Manufactured Product, identifies the drug that is consumed in the substance administration. The medication is identified by means of the LabeledDrug.code or the LabeledDrug.name. The Material entity is used to identify non-drug administered substances such as vaccines and blood products.

Table X: Value set for consumable.typeCode (CNE)

Code	Definition
CSM (consumable) [default]	A substance that is taken up or consumed as part of the substance administration.

Table X: Value set for ManufacturedProduct.classCode (CNE)

Code	Definition
MANU (manufactured) [default]	A manufactured product

Table X: Value set for LabeledDrug.classCode (CNE)

Code	Definition
MMAT (manufactured) [default]	A manufactured material.

Table X: Value set for LabeledDrug.determinerCode (CNE)

Code	Definition
KIND (kind) [default]	The described determiner is used to indicate that the given Entity is taken as a general description of a kind of thing that can be taken in whole, in part, or in multiples.

Table X: Value set for Material.classCode (CNE)

Code	Definition
MMAT (manufactured) [default]	A manufactured material.

Table X: Value set for Material.determinerCode (CNE)

Code	Definition
KIND (kind) [default]	The described determiner is used to indicate that the given Entity is taken as a general description of a kind of thing that can be taken in whole, in part, or in multiples.

4.2.6.9 Supply

A derivative of the RIM Supply class, used for representing the provision of a material by one entity to another.

Table X: Value set for Supply.classCode (CNE)

Code	Definition
SPLY (supply)	The act of dispensing or delivering a product.

Table X: Value set for Supply.moodCode (CNE)

Code	Definition
EVN (event)	The entry defines an actual occurrence of an event.
INT (intent)	The entry is intended or planned.
PRMS (promise)	A commitment to perform the stated entry.
PRP (proposal)	A proposal that the stated entry be performed.
RQO (request)	A request or order to perform the stated entry.

The dispensed product is associated with the Supply act via a product participant, which connects to the same ManufacturedProduct role used for SubstanceAdministration.

Table X: Value set for product.typeCode (CNE)

Code	Definition
PRD (product) [default]	A material target that is brought forth (e.g. dispensed) in the service.

The Supply class represents dispensing, whereas the SubstanceAdministration class represents administration. Prescriptions are complex activities that involve both an administration request to the patient (e.g. take digoxin 0.125mg by mouth once per day) and a supply request to the pharmacy (e.g. dispense 30 tablets, with 5 refills). This should be represented in CDA by a SubstanceAdministration entry that has a component Supply entry. The nested Supply entry can have Supply.independentInd set to "false" to signal that the Supply cannot stand alone, without it's containing SubstanceAdministration. The following example illustrates a prescription representation in CDA.

Example X

<section>
   <text>Digoxin 0.125mg, 1 PO qDay, #30, 5 refills.</text>
   <entry>
      <substanceAdministration classCode="SBADM" moodCode="RQO">
         <effectiveTime xsi:type="PIVL_TS">
            <period value="24" unit="h"/>
         </effectiveTime>
         <routeCode code="PO" 
          codeSystem="2.16.840.1.113883.5.112" 
          codeSystemName="RouteOfAdministration"/>
         <doseQuantity value="1"/>
         <consumable>
            <manufacturedProduct>
               <manufacturedLabeledDrug>
                  <code code="317896006" 
                   codeSystem="2.16.840.1.113883.6.96" 
                   codeSystemName="SNOMED CT" 
                   displayName="Digoxin 125micrograms tablet"/>
               </manufacturedLabeledDrug>
            </manufacturedProduct>
         </consumable>
         <entryRelationship typeCode="COMP">
            <supply classCode="SPLY" moodCode="RQO">
               <repeatNumber>
                  <low value="0"/>
                  <high value="5"/>
               </repeatNumber>
               <independentInd value="false"/>
               <quantity value="30"/>
            </supply>
         </entryRelationship>
      </substanceAdministration>
   </entry>
</section>

4.2.7 Entry Participants

CDA structures and entries can have various participants, some of which are also defined in the CDA header. As described in the discussion of CDA context (see CDA Context), participants propagated from the header can be overridden within the body.

4.2.7.1 author

The author participant (described above, see author), can be ascribed to a CDA section where it overrides the value(s) propagated from the CDA header, or can be ascribed to a CDA entry, where it overrides the value(s) propagated from a CDA section and propagates to nested entries.

4.2.7.2 consumable

The consumable participant is described above (see Entry Acts).

4.2.7.3 informant

The informant participant (described above, see informant), can be ascribed to a CDA section where it overrides the value(s) propagated from the CDA header, or can be ascribed to a CDA entry, where it overrides the value(s) propagated from a CDA section and propagates to nested entries.

4.2.7.4 participant

Can be used to represent any other participant that cannot be represented with one of the more specific participants. The participant can be ascribed to a CDA entry, and propagates to nested CDA entries, unless overridden.

Table X: Value set for participant.typeCode (CNE)

Code	Definition
Any ParticipationType subtype	See vocabulary domain "ParticipationType" for allowable values.

Table X: Value set for participant.contextControlCode (CNE)

Code	Definition
OP (overriding propagating) [default]	The participant overrides associations with the same typeCode. This overriding association will propagate to any descendant Acts reached by conducting ActRelationships. (See section "CDA Context" below.)

A participant is an entity playing one of several possible roles (ParticipantRole class). The entity playing the role is a device (Device class) or other entity (PlayingEntity class). The scoper is any entity (Entity class).

Table X: Value set for ParticipantRole.classCode (CNE)

Code	Definition
Any ROL (RoleClassRoot) subtype	See vocabulary domain "RoleClassRoot" for allowable values.

Table X: Value set for Device.classCode (CNE)

Code	Definition
DEV (device) [default]	An entity used in an activity, without being substantially changed through that activity.
Any DEV subtype	See vocabulary domain "EntityClassDevice" for allowable values.

Table X: Value set for Device.determinerCode (CNE)

Code	Definition
INSTANCE (instance) [default]	The INSTANCE determiner indicates an actual occurrence of an entity, as opposed to the KIND determiner, which refers to the general description of a kind of entity. For example, one can refer to a specific car (a car instance), or one can refer to cars in general (a car kind).

Table X: Value set for PlayingEntity.classCode (CNE)

Code	Definition
ENT (entity) [default]	A physical thing, group of physical things or an organization capable of participating in Acts, while in a role.
Any ENT subtype	See vocabulary domain "EntityClassRoot" for allowable values.

Table X: Value set for PlayingEntity.determinerCode (CNE)

Code	Definition
INSTANCE (instance) [default]	The INSTANCE determiner indicates an actual occurrence of an entity, as opposed to the KIND determiner, which refers to the general description of a kind of entity. For example, one can refer to a specific car (a car instance), or one can refer to cars in general (a car kind).

Table X: Value set for Entity.classCode (CNE)

Code	Definition
ENT (entity) [default]	A physical thing, group of physical things or an organization capable of participating in Acts, while in a role.
Any ENT subtype	See vocabulary domain "EntityClassRoot" for allowable values.

Table X: Value set for Entity.determinerCode (CNE)

Code	Definition
INSTANCE (instance) [default]	The INSTANCE determiner indicates an actual occurrence of an entity, as opposed to the KIND determiner, which refers to the general description of a kind of entity. For example, one can refer to a specific car (a car instance), or one can refer to cars in general (a car kind).

4.2.7.5 performer

The performer is a person who carries out or will carry out a particular act. The performer need not be the principal responsible participant, e.g. a surgery resident operating under supervision of attending surgeon is a performer.

Table X: Value set for performer.typeCode (CNE)

Code	Definition
PRF (performer) [default]	A person who actually and principally carries out or will carry out the action. The traditional order filler is a performer.

4.2.7.6 product

The product participant is described above (see Entry Acts).

4.2.7.7 specimen

A specimen is a part of some entity, typically the subject, that is the target of focused laboratory, radiology or other observations. In many clinical observations, such as physical examination of a patient, the patient is the subject of the observation, and there is no specimen. The specimen participant is only used when observations are made against some substance or object that is taken or derived from the subject.

Table X: Value set for specimen.typeCode (CNE)

Code	Definition
SPC (specimen) [default]	The subject of non-clinical (e.g. laboratory) observation services.

Table X: Value set for SpecimenRole.classCode (CNE)

Code	Definition
SPEC (specimen) [default]	A role played by a material entity that is a specimen for an act.

4.2.7.8 subject

The subject participant (described above, see subject), can be ascribed to a CDA section, or it can be ascribed to a CDA entry, where it overrides the value(s) propagated from a CDA section and propagates to nested entries.

4.2.8 Entry Relationships

4.2.8.1 component

The component relationship has a source of Organizer (see Organizer, and a target that is another CDA entry, and is used to create groupings of CDA entries within an Organizer.

Table X: Value set for component.typeCode (CNE)

Code	Definition
COMP (component) [default]	The associated CDA entry is a component of the organizer.

4.2.8.2 precondition

The precondition class, derived from the ActRelationship class, is used along with the Criterion class to express a condition that must hold true before some over activity occurs.

Table X: Value set for precondition.typeCode (CNE)

Code	Definition
PRCN (precondition) [default]	A requirement to be true before a service is performed.

Table X: Value set for Criterion.classCode (CNE)

Code	Definition
OBS (observation) [default]	Observations are actions performed in order to determine an answer or result value.
Any OBS subtype	See vocabulary domain "ActClassObservation" for allowable values.

Table X: Value set for Criterion.moodCode (CNE)

Code	Definition
EVN.CRT (event criterion) [default]	A criterion or condition that must apply for an associated service to be considered.

4.2.8.3 referenceRange

The referenceRange relationship (described above, see Observation), has a source of Observation, and a target of ObservationRange.

4.2.8.4 entryRelationship

CDA has identified and modeled various link and reference scenarios. These scenarios enable CDA entries to be semantically linked to entries that exist within the same document (by traversing the entryRelationship class) or to objects external to it (by traversing the reference class).

NOTE: The CDA specification permits any CDA entry to relate to any CDA entry using any of the following relationship types. In many cases, this would result in nonsensical relationships. The following table is a guideline for reasonable relationships between CDA entries, and is not a conformance constraint.

Table X: CDA entryRelationship Types

ActRelationship Type	Reasonable Source and Target entries	Comments
CAUS (is etiology for)	(Act | Observation | Procedure | SubstanceAdministration) CAUS (Observation)	Used to show that the source caused the target observation (for instance, source "diabetes mellitus" is the cause of target "kidney disease").
COMP (has component)	(Act | Observation | Procedure | SubstanceAdministration | Supply) COMP (Act | Observation | Procedure | SubstanceAdministration | Suppply)	Used to show that the target is a component of the source (for instance "hemoglobin measurement" is a component of a "complete blood count").
GEVL (evaluates (goal))	(Observation) GEVL (Observation)	Used to link an observation (intent or actual) to a goal to indicate that the observation evaluates the goal (for instance, a source observation of "walking distance" evaluates a target goal of "adequate walking distance").
MFST (is manifestation of)	(Observation) MFST (Observation)	Used to say that the source is a manifestation of the target (for instance, source "hives" is a manifestation of target "penicillin allergy").
REFR (refers to)	(Act | Observation | Procedure | SubstanceAdministration | Supply) REFR (Act | Observation | ObservationMedia | Procedure | RegionOfInterest | SubstanceAdministration | Supply)	Used to show a general relationship between the source and the target, when the more specific semantics of the relationship isn't known.
RSON (has reason)	(Act | Encounter | Observation | Procedure | SubstanceAdministration | Supply) RSON (Act | Encounter | Observation | Procedure | SubstanceAdministration | Supply)	Used to show the reason or rational for a service (for instance source "treadmill test" has reason "chest pain").
SAS (starts after start)	(Act | Encounter | Observation | Procedure | SubstanceAdministration | Supply) SAS (Act | Encounter | Observation | Procedure | SubstanceAdministration | Supply)	The source Act starts after the start of the target Act (for instance source "diaphoresis" starts after the start of target "chest pain").
SPRT (has support)	(Observation) SPRT (Observation | ObservationMedia | RegionOfInterest)	Used to show that the target provides supporting evidence for the source (for instance source "possible lung tumor" has support target "mass seen on chest-x-ray").
SUBJ (has subject)	(Observation | RegionOfInterest) SUBJ (Observation | ObservationMedia)	Used to relate a source region of interest to a target image, or to relate an observation to its subject observation (for instance, source "moderate severity" has subject target "chest pain").

The ActRelationshipType "has subject" is similar to the ParticipationType "subject". Entries that primarily operate on physical subjects use the Participation, whereas entries that primarily operate on other entries use the ActRelationship.

XCRPT (is excerpt of) (Act | Observation) XCRPT (Act | Observation | Procedure | SubstanceAdministration | Supply) Used to show that the source is excerpted from the target (for instance source "hemoglobin value of 12" is an excerpt of target "complete blood count").

The distinction between an excerpt and an informant participant can be blurry — such as in the case of recording a patient's medication history where the clinician may obtain the information from an informant or may excerpt the information from another computer system. An informant (or source of information) is a person who provides relevant information. An informant class is in the header, and can be overridden in the body. An excerpt is a sub portion of some other act.

The entryRelationship.inversionInd can be set to "true" to indicate that the relationship should be interpreted as if the roles of the source and target entries were reversed. In the example in the table above, "treadmill test" RSON (has reason) "chest pain". Inverted, this would have "chest pain" as the source and "treadmill test" as the target: "chest pain" RSON (inverted) "treadmill test". Inversion can be useful when the current context is describing the target of an act relationship that needs to be related back to the source.

The entryRelationship.contextConductionInd differs from the otherwise common use of this attribute (see CDA Context) in that in all other cases where this attribute is used, the value is fixed at "true", whereas here the value is defaulted to "true", and can be changed to "false" when referencing an entry in the same document. Setting the context conduction to false when referencing an entry in the same document keeps clear the fact that the referenced object retains its original context.

4.2.8.5 reference

CDA entries can reference external objects such as external images and prior reports. These external objects are not part of the authenticated document content. They contain sufficient attributes to enable an explicit reference rather than duplicating the entire referenced object. The CDA entry that wraps the external reference can be used to encode the specific portions of the external reference that are addressed in the narrative block.

Each object allows for an identifier and a code, and contains the RIM Act.text attribute, which can be used to store the URL and MIME type of the object. External objects always have a fixed moodCode of "EVN".

The reference class contains the attribute reference.seperatableInd, which indicates whether or not the source is intended to be interpreted independently of the target. The indicator cannot prevent an individual or application from separating the source and target, but indicates the author's desire and willingness to attest to the content of the source if separated from the target. Typically, where seperatableInd is "false", the exchanged package should include the target of the reference so that the recipient can render it.

A description of allowable reference.typeCode values are shown in the following table. As in the table above (CDA entryRelationship Types), the following table is a guideline for reasonable relationships between CDA entries and external objects, and is not a conformance constraint.

Table X: CDA reference Types

ActRelationship Type	Reasonable Source and Target classes	Comments
ELNK (episode link)	(Observation) ELNK (ExternalObservation)	Used to show that the source and the target are part of the same episode (for instance, a diagnosis of "pneumonia" can be linked to an external problem list entry of "pneumonia" to show that the current diagnosis is part of the ongoing episode of pneumonia).
REFR (refers to)	(Act | Observation | Procedure | SubstanceAdministration | Supply) REFR (ExternalAct | ExternalDocument | ExternalObservation | ExternalProcedure)	Used to show a general relationship between the source and the target, when the more specific semantics of the relationship isn't known.
RPLC (replace)	(Act | Encounter | Observation | ObservationMedia | Organizer | Procedure | SubstanceAdministration | Supply) RPLC (ExternalAct | ExternalDocument | ExternalObservation | ExternalProcedure)	Used to indicate that the source entry is a replacement for the target external act.
SPRT (has support)	(Observation) SPRT (ExternalDocument | ExternalObservation)	Used to show that the target provides supporting evidence for the source.
SUBJ (has subject)	(Observation | RegionOfInterest) SUBJ (ExternalObservation)	Used to relate a source region of interest to a target image, or to relate an observation to its subject observation.
XCRPT (is excerpt of)	(Act | Observation) XCRPT (ExternalAct | ExternalDocument | ExternalObservation | ExternalProcedure)	Used to show that the source is excerpted from the target (for instance "the hemoglobin is 10.7" is an excerpt of an externally referenced "complete blood count").

Target classes of the reference relationship include ExternalAct, ExternalDocument, ExternalObservation, and External Procedure.

ExternalAct is a derivative of the RIM Act class, to be used when the other more specific classes are not appropriate.

Table X: Value set for ExternalAct.classCode (CNE)

Code	Definition
ACT (act) [default]	A healthcare service.
Any ACT subtype.	See vocabulary domain "ActClassRoot" for allowable values.

Table X: Value set for ExternalAct.moodCode (CNE)

Code	Definition
EVN (event) [default]	An actual occurrence of an event.

ExternalDocument is a derivative of the RIM Document class, used for representing external documents. ExternalDocument.text is modeled as an ED data type - allowing for the expression of the MIME type of the external document.

Table X: Value set for ExternalDocument.classCode (CNE)

Code	Definition
DOC (document) [default]	The notion of a document comes particularly from the paper world, where it corresponds to the contents recorded on discrete pieces of paper. In the electronic world, a document is a kind of composition that bears resemblance to their paper world counter-parts. Documents typically are meant to be human-readable. HL7's notion of document differs from that described in the W3C XML Recommendation, in which a document refers specifically to the contents that fall between the root element's start-tag and end-tag. Not all XML documents are HL7 documents.
Any DOC subtype	See vocabulary domain "ActClassDocument" for allowable values.

Table X: Value set for ExternalDocument.moodCode (CNE)

Code	Definition
EVN (event) [default]	An actual occurrence of an event.

ExternalObservation is a derivative of the RIM Observation class, used for representing external coded and other observations.

Table X: Value set for ExternalObservation.classCode (CNE)

Code	Definition
OBS (observation) [default]	Observations are actions performed in order to determine an answer or result value.
Any OBS subtype	See vocabulary domain "ActClassObservation" for allowable values.

Table X: Value set for ExternalObservation.moodCode (CNE)

Code	Definition
EVN (event) [default]	An actual occurrence of an event.

ExternalProcedure is a derivative of the RIM Procedure class, used for representing external procedures.

Table X: Value set for ExternalProcedure.classCode (CNE)

Code	Definition
PROC (procedure) [default]	An Act whose immediate and primary outcome (post-condition) is the alteration of the physical condition of the subject.

Table X: Value set for ExternalProcedure.moodCode (CNE)

Code	Definition
EVN (event) [default]	An actual occurrence of an event.

5 CDA Hierarchical Description

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6 CDA XML Implementation

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7 Appendix

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