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"?><NamingSystem xmlns="http://hl7.org/fhir">
<name value="NHS Number"/>
<status value="draft"/>
<kind value="identifier"/>
<date value="2015-05-01"/>
<publisher value="NHS Digital"/>
<contact>
<name value="Interoperability Team"/>
<telecom>
<system value="email"/>
<value value="interoperabilityteam@nhs.net"/>
<use value="work"/>
</telecom>
</contact>
<responsible value="NHS Digital"/>
<description value="NHS Number allocated to the patient."/>
<usage value="A unique patient identifier for everyone registered with the NHS."/>
<uniqueId>
<type value="uri"/>
<value value="https://fhir-test.hl7.org.uk/Id/nhs-number"/>
<preferred value="true"/>
</uniqueId>
<uniqueId>
<type value="oid"/>
<value value="2.16.840.1.113883.2.1.4.1"/>
<preferred value="false"/>
</uniqueId>
</NamingSystem>