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"?><ConceptMap xmlns="http://hl7.org/fhir">
   <id value="CareConnect-MaritalStatus-1"/>
   <url value="https://fhir.hl7.org.uk/STU3/ConceptMap/CareConnect-MaritalStatus-1"/>
   <version value="1.0.0"/>
   <name value="Concept Map - Care Connect Marital Status"/>
   <status value="active"/>
   <date value="2017-08-01T00:00:00+00:00"/>
   <publisher value="HL7 UK"/>
   <description value="A Concept Map from ValueSet Marital Status to NHS Data Dictionary Person Marital Status to aid interpretation."/>
   <copyright value="Copyright © 2016 HL7 UK"/>
   <sourceReference>
      <reference value="https://fhir.hl7.org.uk/STU3/ValueSet/CareConnect-MaritalStatus-1"/>
   </sourceReference>
   <targetReference>
      <reference value="https://fhir.hl7.org.uk/STU3/ValueSet/CareConnect-NHSDataDictionary-PersonMaritalStatus-1"/>
   </targetReference>
   <group>
      <source value="http://hl7.org/fhir/v3/MaritalStatus"/>
      <target value="https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-NHSDataDictionary-PersonMaritalStatus-1"/>
      <element>
         <code value="U"/>
         <display value="unmarried"/>
         <target>
            <code value="S"/>
            <display value="Single"/>
            <equivalence value="equivalent"/>
         </target>
      </element>
      <element>
         <code value="D"/>
         <display value="Divorced"/>
         <target>
            <code value="D"/>
            <display value="Divorced/Person whose Civil Partnership has been dissolved"/>
            <equivalence value="equivalent"/>
         </target>
      </element>
      <element>
         <code value="L"/>
         <display value="Legally Separated"/>
         <target>
            <code value="P"/>
            <display value="Separated"/>
            <equivalence value="equivalent"/>
         </target>
      </element>
      <element>
         <code value="M"/>
         <display value="Married"/>
         <target>
            <code value="M"/>
            <display value="Married/Civil Partner"/>
            <equivalence value="equivalent"/>
         </target>
      </element>
      <element>
         <code value="S"/>
         <display value="Never Married"/>
         <target>
            <code value="S"/>
            <display value="Single"/>
            <equivalence value="equivalent"/>
         </target>
      </element>
      <element>
         <code value="W"/>
         <display value="Widowed"/>
         <target>
            <code value="W"/>
            <display value="Widowed/Surviving Civil Partner"/>
            <equivalence value="equivalent"/>
         </target>
      </element>
   </group>
   <group>
      <source value="http://hl7.org/fhir/v3/NullFlavor"/>
      <target value="https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-NHSDataDictionary-PersonMaritalStatus-1"/>
      <element>
         <code value="UNK"/>
         <display value="unknown"/>
         <target>
            <code value="N"/>
            <display value="Not disclosed"/>
            <equivalence value="equivalent"/>
         </target>
      </element>
   </group>
</ConceptMap>