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-MedicationFlag-1"></id>
<text>
<status value="generated"></status>
</text>
<url value="https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-MedicationFlag-1"></url>
<version value="1.0.0"></version>
<name value="Care Connect Medication Flag"></name>
<status value="draft"></status>
<date value="2017-08-01T00:00:00+00:00"></date>
<publisher value="HL7 UK"></publisher>
<description value="A CodeSystem to identify detail codes for flagged medication issues."></description>
<copyright value="Copyright © 2016 HL7 UK"></copyright>
<caseSensitive value="true"></caseSensitive>
<content value="complete"></content>
<concept>
<code value="do-not-discontinue"></code>
<display value="Do Not discontinue Medication"></display>
</concept>
<concept>
<code value="continue-indefinitely"></code>
<display value="Continue Indefinitely"></display>
</concept>
</CodeSystem>