{
    "resourceType": "Observation",
    "id": "Observation-Necrosis-Example",
    "status": "final",
    "code": {
        "coding":  [
            {
                "system": "http://snomed.info/sct",
                "code": "405921002",
                "display": "Percentage of neoplasm involved by necrosis (observable entity)"
            }
        ]
    },
    "subject": {
        "reference": "Patient/Patient-ZelmaHadjkiss-Example",
        "identifier": {
            "system": "https://fhir.nhs.uk/Id/nhs-number",
            "value": "9449307555"
        }
    },
    "specimen": {
        "identifier": {
            "system": "https://fhir.add.nhs.uk/Id/specimenId",
            "value": "RA257630"
        }
    },
    "valueQuantity": {
        "value": 5,
        "unit": "%",
        "system": "http://unitsofmeasure.org",
        "code": "%"
    },
    "effectiveDateTime": "2023-09-08"
}

<Observation xmlns="http://hl7.org/fhir">
    <id value="Observation-Necrosis-Example" />
    <status value="final" />
    <code>
        <coding>
            <system value="http://snomed.info/sct" />
            <code value="405921002" />
            <display value="Percentage of neoplasm involved by necrosis (observable entity)" />
        </coding>
    </code>
    <subject>
        <reference value="Patient/Patient-ZelmaHadjkiss-Example" />
        <identifier>
            <system value="https://fhir.nhs.uk/Id/nhs-number" />
            <value value="9449307555" />
        </identifier>
    </subject>
    <effectiveDateTime value="2023-09-08" />
    <valueQuantity>
        <value value="5" />
        <unit value="%" />
        <system value="http://unitsofmeasure.org" />
        <code value="%" />
    </valueQuantity>
    <specimen>
        <identifier>
            <system value="https://fhir.add.nhs.uk/Id/specimenId" />
            <value value="RA257630" />
        </identifier>
    </specimen>
</Observation>

Propose a change to Observation-Necrosis-Example