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+# Property Configuration Files
+
+Each JSON file in this folder is a property configuration file for reference
+Vehicle HAL. They contain VehiclePropConfig information along with initial
+value information.
+
+## JSON schema
+
+Each JSON file must be in a schema like the following example:
+(The comment starting with "//" is for documentation only and must be removed
+from the actual JSON file. The "comment" field is used for comment in the
+actual JSON file and will be ignored by the parser)
+
+```
+{
+    // (number) The version for the JSON schema.
+    "apiVersion": 1,
+    // (non-empty array of objects) The property configuration list.
+    //
+    // Each object is a configuration for one property.
+    "properties": [
+        {
+            // (number/string) The ID for the property.
+            // This value is defined in a string value
+            // which represents a constant value, see the "JSON Number-type
+            // Field Values" section for detail.
+            "property": "VehicleProperty::INFO_FUEL_CAPACITY",
+            // (optional, number/string) The access mode for the property.
+            // If specified, this overwrite the default access mode specified in
+            // VehicleProperty.aidl. Must be specified for vendor properties.
+            "access": "VehiclePropertyAccess::READ",
+            // (optional, number/string) The change mode for the property.
+            // If specified, this overwrite the default change mode specified in
+            // VehicleProperty.aidl. Must be specified for vendor properties.
+            "changeMode": "VehiclePropertyChangeMode::STATIC",
+            // (optional, string) The config string.
+            "configString": "blahblah",
+            // (optional, array of number/string) The config array.
+            "configArray": [1, 2, "Constants::HVAC_ALL"],
+            // (optional, object) The default value for the property.
+            // If not specified, the property will be shown as unavailable
+            // until its value is set.
+            "defaultValue": {
+                // (optional, array of int number/string) Int values.
+                "int32Values": [1, 2, "Constants::HVAC_ALL"],
+                // (optional, array of int number/string) Long values.
+                "int64Values": [1, 2],
+                // (optional, array of float number/string) Float values.
+                "floatValues": [1.1, 2.2],
+                // (optional, string) String value.
+                "stringValue": "test"
+            },
+            // (optional, number/string) The minimum sample rate in HZ.
+            // Only work for VehiclePropertyChangeMode::CONTINUOUS property.
+            // Must be specified for continuous property.
+            "minSampleRate": 1,
+            // (optional, number/string) The maximum sample rate in HZ.
+            // Only work for VehiclePropertyChangeMode::CONTINUOUS property.
+            // Must be specified for continuous property.
+            "maxSampleRate": 10,
+            // (optional, array of objects) The area configs.
+            "areas:" [
+                {
+                    // (number/string) The area ID.
+                    "areaId": "Constants::DOOR_1_LEFT",
+                    // (optional number/string) The minimum int value.
+                    "minInt32Value": 1,
+                    // (optional number/string) The maximum int value.
+                    "maxInt32Value": 10,
+                    // (optional number/string) The minimum long value.
+                    "minInt64Value": 1,
+                    // (optional number/string) The maximum long value.
+                    "maxInt64Value": 10,
+                    // (optional number/string) The minimum float value.
+                    "minFloatValue": 1,
+                    // (optional number/string) The maximum float value.
+                    "maxFloatValue": 10,
+                    // (optional object) The default value for this area.
+                    // Uses the same format as the "defaultValue" field for
+                    // property object. If specified, this overwrite the global
+                    // defaultValue.
+                    "defaultValue": {
+                        "int32Values": [1, 2, "Constants::HVAC_ALL"],
+                        "int64Values": [1, 2],
+                        "floatValues": [1.1, 2.2],
+                        "stringValue": "test"
+                    }
+                }
+            ]
+        }
+     ]
+}
+```
+
+## JSON Number-type Field Values
+
+For number type field values, they can either be defined as a numeric number,
+e.g., `{"minInt32Value": 1}` or be defined as a string which represents a
+defined constant value, e.g.,
+`{"property": "VehicleProperty::INFO_FUEL_CAPACITY"}`.
+
+For constant values, they must be a string in the format of `XXX::XXX`, where
+the field before `::` is the constant type, and the field after `::` is the
+variable name.
+
+We support the following constant types:
+
+* VehiclePropertyAccess
+
+* VehiclePropertyChangeMode
+
+* VehicleGear
+
+* VehicleAreaWindow
+
+* VehicleOilLevel
+
+* VehicleUnit
+
+* VehicleSeatOccupancyState
+
+* VehicleHvacFanDirection
+
+* VehicleApPowerStateReport
+
+* VehicleTurnSignal
+
+* VehicleVendorPermission
+
+* EvsServiceType
+
+* EvsServiceState
+
+* EvConnectorType
+
+* VehicleProperty
+
+* GsrComplianceRequirementType
+
+* VehicleIgnitionState
+
+* FuelType
+
+* Constants
+
+Every constant type except "Constants" corresponds to a enum defined in Vehicle
+HAL interfac. E.g. "VehicleProperty" corresponds to the enums defined in
+"VehicleProperty.aidl".
+
+"Constants" type refers to the constant variables defined in the paresr.
+Specifically, the "CONSTANTS_BY_NAME" map defined in "JsonConfigLoader.cpp".