This is a HL7 FHIR server, and as you appear to be accessing this page from a web browser you are seeing a HTML version of the requested resource(s). You can also access this URL from a FHIR client as a ReSTful API call. For more details please see the HL7 FHIR specification.
<CodeSystem xmlns="http://hl7.org/fhir">
<id value="CareConnect-NHSNumberVerificationStatus-1"></id>
<text>
<status value="generated"></status>
</text>
<extension url="http://hl7.org/fhir/StructureDefinition/codesystem-sourceReference">
<valueUri value="http://www.datadictionary.nhs.uk/data_dictionary/data_field_notes/n/nhs/nhs_number_status_indicator_code_de.asp?shownav=1"></valueUri>
</extension>
<url value="https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-NHSNumberVerificationStatus-1"></url>
<version value="1.1.0"></version>
<name value="Care Connect NHS Number Verification Status"></name>
<status value="draft"></status>
<date value="2018-11-02T00:00:00+00:00"></date>
<publisher value="HL7 UK"></publisher>
<description value="A CodeSystem that identifies the trace status of the NHS number. This CodeSystem is comprised of codes from the NHS Data Model and Dictionary: NHS Number Status Indicator Code."></description>
<copyright value="Copyright © 2016 HL7 UK"></copyright>
<caseSensitive value="true"></caseSensitive>
<content value="complete"></content>
<concept>
<code value="01"></code>
<display value="Number present and verified"></display>
</concept>
<concept>
<code value="02"></code>
<display value="Number present but not traced"></display>
</concept>
<concept>
<code value="03"></code>
<display value="Trace required"></display>
</concept>
<concept>
<code value="04"></code>
<display value="Trace attempted - No match or multiple match found"></display>
</concept>
<concept>
<code value="05"></code>
<display value="Trace needs to be resolved - (NHS number or patient detail conflict)"></display>
</concept>
<concept>
<code value="06"></code>
<display value="Trace in progress"></display>
</concept>
<concept>
<code value="07"></code>
<display value="Number not present and trace not required"></display>
</concept>
<concept>
<code value="08"></code>
<display value="Trace postponed (baby under six weeks old)"></display>
</concept>
</CodeSystem>