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.
{
  "resourceType": "CodeSystem",
  "id": "CareConnect-ReferralRequestMethod-1",
  "url": "https://fhir.hl7.org.uk/STU3/CodeSystem/CareConnect-ReferralRequestMethod-1",
  "version": "1.0.0",
  "name": "Care Connect Referral Request Method",
  "status": "draft",
  "date": "2019-07-16T17:43:00+00:00",
  "publisher": "HL7 UK",
  "description": "A CodeSystem to identify the form in which a referral is sent and received.",
  "copyright": "Copyright © 2019 HL7 UK",
  "caseSensitive": true,
  "content": "complete",
  "concept": [
    {
      "code": "1",
      "display": "Fax"
    },
    {
      "code": "2",
      "display": "Phone"
    },
    {
      "code": "3",
      "display": "Secure Messaging"
    },
    {
      "code": "4",
      "display": "Secure Email"
    },
    {
      "code": "5",
      "display": "Letter"
    },
    {
      "code": "6",
      "display": "NHS E-Referral Service"
    },
    {
      "code": "7",
      "display": "Self Referral"
    }
  ]
}