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="GPConnect-SecondaryListValues-1"></id>
<text>
<status value="generated"></status>
</text>
<url value="https://fhir.hl7.org.uk/STU3/CodeSystem/GPConnect-SecondaryListValues-1"></url>
<version value="1.0.0"></version>
<name value="GPConnect Secondary List Values"></name>
<status value="active"></status>
<date value="2020-09-25T17:21:47+00:00"></date>
<publisher value="HL7 UK"></publisher>
<description value="A CodeSystem to identify the secondary list values."></description>
<copyright value="Copyright © 2020 HL7 UK"></copyright>
<caseSensitive value="true"></caseSensitive>
<content value="complete"></content>
<concept>
<code value="consultations-allergies-contained-in-consultations"></code>
<display value="Consultations - allergies contained in consultations"></display>
</concept>
<concept>
<code value="consultations-allergies-that-have-been-ended-contained-in-consultations"></code>
<display value="Consultations - allergies that have been ended contained in consultations"></display>
</concept>
<concept>
<code value="consultations-diary-entries-contained-in-consultations"></code>
<display value="Consultations - diary entries contained in consultations"></display>
</concept>
<concept>
<code value="consultations-documents-contained-in-consultations"></code>
<display value="Consultations - documents contained in consultations"></display>
</concept>
<concept>
<code value="consultations-immunisations-contained-in-consultations"></code>
<display value="Consultations - immunisations contained in consultations"></display>
</concept>
<concept>
<code value="consultations-investigations-contained-in-consultations"></code>
<display value="Consultations - investigations contained in consultations"></display>
</concept>
<concept>
<code value="consultations-medications-contained-in-consultations"></code>
<display value="Consultations - medications contained in consultations"></display>
</concept>
<concept>
<code value="consultations-outbound-referrals-in-consultations"></code>
<display value="Consultations - outbound referrals in consultations"></display>
</concept>
<concept>
<code value="consultations-problems-contained-in-consultations"></code>
<display value="Consultations - problems contained in consultations"></display>
</concept>
<concept>
<code value="consultations-uncategorised-data-contained-in-consultations"></code>
<display value="Consultations - uncategorised data contained in consultations"></display>
</concept>
<concept>
<code value="problems-allergies-related-to-problems"></code>
<display value="Problems - allergies related to problems"></display>
</concept>
<concept>
<code value="problems-allergies-that-have-been-ended-related-to-problems"></code>
<display value="Problems - allergies that have been ended related to problems"></display>
</concept>
<concept>
<code value="problems-consultations-related-to-problems"></code>
<display value="Problems - consultations related to problems"></display>
</concept>
<concept>
<code value="problems-diary-entries-related-to-problems"></code>
<display value="Problems - diary entries related to problems"></display>
</concept>
<concept>
<code value="problems-documents-related-to-problems"></code>
<display value="Problems - documents related to problems"></display>
</concept>
<concept>
<code value="problems-immunisations-related-to-problems"></code>
<display value="Problems - immunisations related to problems"></display>
</concept>
<concept>
<code value="problems-investigations-related-to-problems"></code>
<display value="Problems - investigations related to problems"></display>
</concept>
<concept>
<code value="problems-medications-related-to-problems"></code>
<display value="Problems - medications related to problems"></display>
</concept>
<concept>
<code value="problems-outbound-referrals-related-to-problems"></code>
<display value="Problems - outbound referrals related to problems"></display>
</concept>
<concept>
<code value="problems-linked-problems-not-relating-to-the-primary-query"></code>
<display value="Problems - linked problems not relating to the primary query"></display>
</concept>
<concept>
<code value="problems-uncategorised-data-related-to-problems"></code>
<display value="Problems - uncategorised data related to problems"></display>
</concept>
</CodeSystem>