The tool data package contains the AnalogInputRange2/3:
Size in Data type Meaning Notes
4 integer Package length (bytes) 37 bytes
1 uchar Package type Type is 2 (“Tool Data”)
1 char AnalogInputRange2
1 char AnalogInputRange3
Is it correct that the value can only be zero or one with the meaning that the input is measuring current (0) or voltage (1)?
That is correct.
It is quite comparable to the URscript codes used for same functionality, which also use 0/1 for current/voltage.