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-DeliveryChannel-1"></id>
   <text>
      <status value="generated"></status>
   </text>
   <url value="https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-DeliveryChannel-1"></url>
   <version value="1.0.0"></version>
   <name value="CareConnect-DeliveryChannel-1"></name>
   <status value="draft"></status>
   <date value="2019-12-02T12:10:00+00:00"></date>
   <publisher value="HL7 UK"></publisher>
   <description value="A CodeSystem that identifies the delivery channel of an appointment."></description>
   <copyright value="Copyright © 2019 HL7 UK"></copyright>
   <caseSensitive value="true"></caseSensitive>
   <content value="complete"></content>
   <concept>
      <code value="In-person"></code>
      <display value="In-person"></display>
   </concept>
   <concept>
      <code value="Telephone"></code>
      <display value="Telephone"></display>
   </concept>
   <concept>
      <code value="Video"></code>
      <display value="Video"></display>
   </concept>
</CodeSystem>