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.
<?xml version="1.0" encoding="UTF-8" standalone="no"?><CodeSystem xmlns="http://hl7.org/fhir">
   <id value="CareConnect-NHSDataDictionary-PersonMaritalStatus-1"/>
   <extension url="http://hl7.org/fhir/StructureDefinition/codesystem-sourceReference">
      <valueUri value="http://www.datadictionary.nhs.uk/data_dictionary/attributes/p/person/person_marital_status_code_de.asp?shownav=1"/>
   </extension>
   <url value="https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-NHSDataDictionary-PersonMaritalStatus-1"/>
   <version value="1.0.0"/>
   <name value="NHS Data Model and Dictionary Person Marital Status Code"/>
   <status value="active"/>
   <date value="2016-08-03T00:00:00+01:00"/>
   <publisher value="HL7 UK"/>
   <description value="An indicator to identify the legal marital status of a Person."/>
   <copyright value="Copyright © 2016 HL7 UK"/>
   <caseSensitive value="true"/>
   <content value="complete"/>
   <concept>
      <code value="S"/>
      <display value="Single"/>
   </concept>
   <concept>
      <code value="M"/>
      <display value="Married/Civil Partner"/>
   </concept>
   <concept>
      <code value="D"/>
      <display value="Divorced/Person whose Civil Partnership has been dissolved"/>
   </concept>
   <concept>
      <code value="W"/>
      <display value="Widowed/Surviving Civil Partner"/>
   </concept>
   <concept>
      <code value="P"/>
      <display value="Separated"/>
   </concept>
   <concept>
      <code value="N"/>
      <display value="Not disclosed"/>
   </concept>
</CodeSystem>