Relative strength.  

 | Data byte | Description                         | 
 | :---------: | -----------                       | 
 | 0         | Data coding.                        | 
 | 1-7       | Data with format defined by byte 0. | 

### Coding of units (Level I)

 | Code | Description  | 
 | :----: | ----------- | 
 | 0    | **Byte count = 2**: Min = 0, Max = 255 <br> **Byte count = 3**: Min = 0, Max = 65535 <br> and so on... | 
 | 1    | db (decibel) | 
 | 2    | dbV (decibel volts) | 
 | 3    | Undefined | 

Units for Level II are the same as for Level I for the first four units.
