json_schema: {
      "properties": {
          "acquisition_source": {
              "description": "Source of acquisition (former 541)",
              "id": "#acquisition_source",
              "properties": {
                  "date": {
                      "_format": "date",
                      "description": "Date of acquisition",
                      "type": "string"
                  },
                  "email": {
                      "_format": "email",
                      "description": "Email of submitter",
                      "type": "string"
                  },
                  "method": {
                      "description": "Method of acquisition",
                      "enum": [
                          "OAI",
                          "batchupload",
                          "submission"
                      ]
                  },
                  "source": {
                      "description": "Source of acquisition (e.g. ID of the user)",
                      "type": "string"
                  },
                  "submission_number": {
                      "description": "Internal submission number",
                      "type": "integer"
                  }
              },
              "type": "object"
          }
      }
  }