Use the following as an empty Diagnostic Results sections.
<component>
<!--Diagnostic Results-->
<section>
<templateId root="2.16.840.1.113883.3.88.11.83.122"/>
<templateId root="1.3.6.1.4.1.19376.1.5.3.1.3.28"/>
<!--Diagnostic Results section template-->
<code code="30954-2" codeSystem="2.16.840.1.113883.6.1" codeSystemName="LOINC" displayName="Results"/>
<title>Diagnostic Results</title>
<entry typeCode="DRIV">
<organizer classCode="CLUSTER" moodCode="EVN">
<templateId root="2.16.840.1.113883.10.20.1.32"/>
<!--Result organizer template -->
<id root="2.16.840.1.113883.10.20.1.32.1578"/>
<code nullFlavor="NA"/>
<statusCode code="completed"/>
<effectiveTime value="20140221"/>
<component>
<procedure classCode="PROC" moodCode="EVN">
<templateId assigningAuthorityName="HITSP C83" root="2.16.840.1.113883.3.88.11.83.17"/>
<templateId assigningAuthorityName="CCD" root="2.16.840.1.113883.10.20.1.29"/>
<templateId assigningAuthorityName="IHE PCC" root="1.3.6.1.4.1.19376.1.5.3.1.4.19"/>
<id root="2.16.840.1.113883.10.20.1.32.123435"/>
<code nullFlavor="UNK">
<originalText>
<reference value="Unknown"/>
</originalText>
</code>
<text>
<reference value="Unknown"/>
</text>
<statusCode code="completed"/>
<effectiveTime nullFlavor="UNK"/>
</procedure>
</component>
<component>
<observation classCode="OBS" moodCode="EVN">
<templateId assigningAuthorityName="HITSP C83" root="2.16.840.1.113883.3.88.11.83.15.1"/>
<templateId assigningAuthorityName="CCD" root="2.16.840.1.113883.10.20.1.31"/>
<templateId assigningAuthorityName="IHE PCC" root="1.3.6.1.4.1.19376.1.5.3.1.4.13"/>
<id root="2.16.840.1.113883.10.20.1.32.23155"/>
<code code="UNK" nullFlavor="UNK"/>
<text>
<reference value="Unknown"/>
</text>
<statusCode code="completed"/>
<effectiveTime nullFlavor="UNK"/>
</observation>
</component>
</organizer>
</entry>
</section>
</component>
Note: For the NIST validator the order is important.
Example:
Bad - <code nullFlavor="UNK" code="UNK"/>
Good - <code code="UNK" nullFlavor="UNK"/>