Each data entry specifies a datatype from the following set (from Franca IDL). Datatypes shall not be used for branch entry

Supported datatypes

Name Datatype Min Max
uint8 unsigned 8-bit integer 0 255
int8 signed 8-bit integer -128 127
uint16 unsigned 16-bit integer 0 65535
int16 signed 16-bit integer -32768 32767
uint32 unsigned 32-bit integer 0 4294967295
int32 signed 32-bit integer -2147483648 2147483647
uint64 unsigned 64-bit integer 0 2^64 - 1
int64 signed 64-bit integer -2^63 2^63 - 1
boolean boolean value 0/false 1/true
float IEEE 754-2008 binary32 floating point number -3.40e 38 3.40e 38
double IEEE 754-2008 binary64 floating point number -1.80e 308 1.80e 308
string character string (unicode) n/a n/a


Strings in VSS supports the unicode character set. Actual encoding like UTF-8 or UTF-16 is not specified by VSS, that is to up to the Protocol/API/SDK implementing VSS support to decide.


Besides the datatypes described above, VSS supports as well the concept of arrays, as a collection of elements based on the data entry definition, wherein it’s specified. By default the size of the array is undefined. By the optional keyword arraysize the size of the array can be specified. The following syntax shall be used to declare an array:

# Array of datatype uint32, by default size of the array is undefined
datatype: uint32[]
# Optional: specified number of elements in the array
arraysize: 5

An example for the usage of arrays is Vehicle.OBD.DTCList which contains a list of Diagnostic Trouble Codes (DTCs) present in a vehicle.


VSS struct support is further described on this page.

Data Streams

Data Entries, which describe sensors offering binary streams (e.g. cameras), are not supported directly by VSS with a dedicated datatype. Instead, they are described through the meta data about the sensor itself and how to retrieve the corresponding data stream.

A camera can be a good example of it. The Data Entry for the camera and the corresponding video stream could look like:

  type: branch
  description: Information about the camera and how to connect to the video stream

  type: actuator
  datatype: boolean
  description: If the camera is active, the client is able to retrieve the video stream

  type: sensor
  datatype: string
  description: URI for retrieving the video stream, with information on how to access the stream (e.g. protocol,  data format, encoding, etc.)

In this example, it shows the usage of meta data about the status of the sensor. The camera can be set to active through the same data entry (actuator). A dynamic data entry (sensor) is used for the URI of the video stream. Information on how to access the stream is expected.