List of Sensor X-pin value AND value_type

It took me a while to find the X-pin value of for example the NO2 sensor
NO2-A43F. The way I have found it is by selecting this sensor in and enable expert fields. This shows that it is number 17. But I would also need the value-type name for this sensor (for and Madavi) to be able to construct the correct json for posting the sensor data.
Where can I find this information?