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.
<ValueSet xmlns="http://hl7.org/fhir">
   <id value="CareConnect-AllergyVerificationStatus-1"></id>
   <text>
      <status value="generated"></status>
   </text>
   <extension url="http://hl7.org/fhir/StructureDefinition/valueset-map">
      <valueReference>
         <reference value="https://fhir.hl7.org.uk/STU3/ConceptMap/CareConnect-AllergyVerificationStatus-1"></reference>
      </valueReference>
   </extension>
   <extension url="http://hl7.org/fhir/StructureDefinition/valueset-sourceReference">
      <valueUri value="http://hl7.org/fhir/ValueSet/allergy-verification-status"></valueUri>
   </extension>
   <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-wg">
      <valueCode value="pc"></valueCode>
   </extension>
   <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm">
      <valueInteger value="3"></valueInteger>
   </extension>
   <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-ballot-status">
      <valueString value="Informative"></valueString>
   </extension>
   <url value="https://fhir.hl7.org.uk/STU3/ValueSet/CareConnect-AllergyVerificationStatus-1"></url>
   <identifier>
      <system value="urn:ietf:rfc:3986"></system>
      <value value="urn:oid:2.16.840.1.113883.4.642.3.115"></value>
   </identifier>
   <version value="3.0.1"></version>
   <name value="AllergyIntoleranceVerificationStatus"></name>
   <status value="active"></status>
   <date value="2017-04-19T07:44:47+10:00"></date>
   <publisher value="HL7 (FHIR Project)"></publisher>
   <contact>
      <telecom>
         <system value="url"></system>
         <value value="http://hl7.org/fhir"></value>
      </telecom>
   </contact>
   <description value="Assertion about certainty associated with a propensity, or potential risk, of a reaction to the identified substance."></description>
   <copyright value="Copyright © HL7.org 2011+"></copyright>
   <compose>
      <include>
         <system value="http://hl7.org/fhir/allergy-verification-status"></system>
         <concept>
            <code value="unconfirmed"></code>
            <display value="Unconfirmed"></display>
         </concept>
         <concept>
            <code value="confirmed"></code>
            <display value="Confirmed"></display>
         </concept>
      </include>
   </compose>
</ValueSet>