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Dataset-JSON is using lowerCamelCase notation for attribute names, comparing to Dataset-XML PascalCase (e.g., clinicalData vs ClinicalData).

JSON format cannot specify does not allow to specify or control order of attributes. For the efficiency of working with the file format Despite of that, as most JSON engines allow to control the order of attributes it is strongly recommended to follow the attribute order specified in details. . The reason for that is that due to a possible large size of Dataset-JSON files, following the specified order will enable a software using steaming approaches to read the file to work in an efficient and fast way.

Top Level Attributes

At the top level of Dataset-JSON object, there are technical attributes and two main optional attributes: clinicalData and referenceData, corresponding to Dataset-XML elements. At least 1 of the main attributes must be provided. Subject data is stored in clinicalData and non-subject data is stored in referenceData.

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{
    "fileOID": "www.sponsor.xyz.org.project123.final",
    "creationDateTime": "2023-03-22T11:53:27",
    "asOfDateTime": "2023-02-15T10:23:15",
    "originator": "Sponsor XYZ",
    "sourceSystem": "Software ABC",
    "sourceSystemVersion": "1.0.0",
    "datasetJSONVersion": "",
    "clinicalData": { ... },
    "referenceData": { ... }
}

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Both clinicalData and referenceData have the same structure. Each of these attributes contains study and metadata OIDs as well as , optional reference to the metadata file and an object describing an item group (dataset). The following attributes are defined on this level

Values of the studyOID and metaDataVersionOID must match corresponding values in the Define-XML file.

{
    "clinicalData": {
        "studyOID": "xxx",
        "metaDataVersionOID": "xxx",
        "metaDataRef": "https://metadata.location.org/api.link",
        "itemGroupData": { ... }
}

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itemGroupData is an object with attributes a single attribute corresponding to an individual datasetsdataset. The attribute name is OID of a described dataset, which must be the same as OID of the corresponding itemGroup in the Define-XML file.

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The dataset description contains basic information about the dataset itself and its items.

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"IG.DM": {
    "records": 100,
    "name": "DM",
    "label": "Demographics",
    "items": [ ... ],
    "itemData": [ ... ]
}

items is an array of basic information about dataset variables. The order of elements in the array must be the same as the order of variables in the described dataset. The first element always describes the Record Identifier (ITEMGROUPDATASEQ).

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"items": [    
    {
        "OID": "ITEMGROUPDATASEQ",
        "name": "ITEMGROUPDATASEQ",
        "label": "Record identifier",
        "type": "integer",
    },
    {
        "OID": "IT.DM.STUDYID",
        "name": "STUDYID",
        "label": "Study Identifier",
        "type": "string",
        "length": 12,
        "keySequence": "1",
    },
    ...
]

itemData is an array of records with variables values. Each record itself is also represented as an array of variables values. The first value is a unique sequence number for each record in the dataset.

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The following is a full example of a Dataset-JSON file:

{
    "fileOID": "www.sponsor.org.project123.final",
    "creationDateTime": "2023-03-22T11:53:27",
    "asOfDateTime": "2023-02-15T10:23:15",
    "originator": "Sponsor XYZ",
    "sourceSystem": "Software ABC",
    "sourceSystemVersion": "1.2.3",
    "datasetJSONVersion": "1.0.0",
    "clinicalData": {
        "studyOID": "xxx",
        "metaDataVersionOID": "xxx",
        "metaDataRef": "https://metadata.location.org/api.link",
        "itemGroupData": {
            "IG.DM": {
                "records": 600,
                "name": "DM",
                "label": "Demographics",
                "items": [                      
                    {"OID": "ITEMGROUPDATASEQ", "name": "ITEMGROUPDATASEQ", "label": "Record identifier", "type": "integer"},
                    {"OID": "IT.STUDYID", "name": "STUDYID", "label": "Study identifier", "type": "string", "length": 7, "keySequence": 1}, 
                    {"OID": "IT.USUBJID", "name": "USUBJID", "label": "Unique Subject Identifier", "type": "string", "length": 3, "keySequence": 2}, 
                    {"OID": "IT.DOMAIN", "name": "DOMAIN", "label": "Domain Identifier", "type": "string", "length": 2},
                    {"OID": "IT.AGE", "name": "AGE", "label": "Subject Age", "type": "integer", "length": 2}
                ],
                "itemData": [
                    [1, "MyStudy", "001", "DM", 56],
                    [2, "MyStudy", "002", "DM", 26],
                    ...
                ]
            }
        }
    },
    "referenceData": {
        ... Same structure as clinical data
    }
}