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.
<ConceptMap xmlns="http://hl7.org/fhir">
   <id value="CareConnect-AllergyVerificationStatus-1"></id>
   <text>
      <status value="generated"></status>
   </text>
   <url value="https://fhir.hl7.org.uk/STU3/ConceptMap/CareConnect-AllergyVerificationStatus-1"></url>
   <version value="1.1.0"></version>
   <name value="Concept Map - Allergy Verification Status"></name>
   <status value="draft"></status>
   <date value="2018-11-14T00:00:00+00:00"></date>
   <publisher value="HL7 UK"></publisher>
   <description value="A Concept Map from ValueSet Allergy Verification Status to Allergy Certainity to aid interpretation."></description>
   <copyright value="Copyright © 2016 HL7 UK"></copyright>
   <sourceReference>
      <reference value="https://fhir.hl7.org.uk/STU3/ValueSet/CareConnect-AllergyVerificationStatus-1"></reference>
   </sourceReference>
   <targetReference>
      <reference value="https://fhir.hl7.org.uk/STU3/ValueSet/CareConnect-AllergyCertainty-1"></reference>
   </targetReference>
   <group>
      <source value="http://hl7.org/fhir/allergy-verification-status"></source>
      <target value="http://snomed.info/sct"></target>
      <element>
         <code value="unconfirmed"></code>
         <display value="Unconfirmed"></display>
         <target>
            <code value="385434005"></code>
            <display value="Improbable diagnosis"></display>
            <equivalence value="equivalent"></equivalence>
         </target>
      </element>
      <element>
         <code value="unconfirmed"></code>
         <display value="Unconfirmed"></display>
         <target>
            <code value="2931005"></code>
            <display value="Probable diagnosis"></display>
            <equivalence value="equivalent"></equivalence>
         </target>
      </element>
      <element>
         <code value="confirmed"></code>
         <display value="Confirmed"></display>
         <target>
            <code value="255545003"></code>
            <display value="Definite"></display>
            <equivalence value="equivalent"></equivalence>
         </target>
      </element>
      <element>
         <code value="confirmed"></code>
         <display value="Confirmed"></display>
         <target>
            <code value="410605003"></code>
            <display value="Confirmed present"></display>
            <equivalence value="equivalent"></equivalence>
         </target>
      </element>
   </group>
</ConceptMap>