Modbus climates scale offset, not clear in documentation

Hello,
in the Home Assistant Modbus docs (Modbus - Home Assistant) in the climate section there are two parameter that make me mumbling.
I admit I have not tested it yet because the bus is not ready yet but I would like to know if somebody can explain me:

  • scale
  • offset

I fully understand how to use it and how it works but looking at the docs it is not clear for me if they apply to target_temp_register or realtime temperature.

    climates:
      - name: "climate1"
        unique_id: climate1
        device_address: 1 
        address: 1606 #register for current temperature
        input_type: holding
        target_temp_register: 1602 #register for target temperature
        max_temp: 30
        min_temp: 17
        offset: -20
        scale: 0.5
        temp_step: 1
        temperature_unit: C

In the code, above, will the offset and scale have effect on current temperature or on target temperature or on both?
If I want to apply scale and offset on the current temperature only should I use the following code?
Or again if these parameters apply on both I have to find a different way.

    climates:
      - name: "climate1"
        unique_id: climate1
        device_address: 1 
        address: 1606 #register for current temperature
        offset: -20
        scale: 0.5
        input_type: holding
        target_temp_register: 1602 #register for target temperature
        max_temp: 30
        min_temp: 17
        temp_step: 1
        temperature_unit: C