## ServiceTypeReferenceURI variable

Extension URI holding a `Reference<HealthcareService>` on a `serviceType` CodeableConcept.

In R5/R6, `serviceType` attributes change from `CodeableConcept[]` to `CodeableReference<HealthcareService>`. We approximate that in R4 with this extension.

Example: a Schedule whose serviceType refers to a HealthcareService:

```json
{
  "resourceType": "Schedule",
  "actor": [{ "reference": "Practitioner/abc" }],
  "serviceType": [\
    {\
      "extension": [\
        {\
          "url": "https://medplum.com/fhir/service-type-reference",\
          "valueReference": { "reference": "HealthcareService/123" }\
        }\
      ]\
    }\
  ]
}
```

**Signature:**

```typescript
ServiceTypeReferenceURI = "https://medplum.com/fhir/service-type-reference"
```

- [ServiceTypeReferenceURI variable](/content/docs/sdk/core.servicetypereferenceuri#servicetypereferenceuri-variable/index.html)