Stanford Research Systems SR860 Operation Manual page 151

Chapter 4 Programming 133
The requested values are returned in a single string with the values separated by commas
and in the order in which they were requested. In this example, the returned string might
be
0.951359,0.0253297,1.234
The first value is X, the second is Y and the third is Aux In1.
Not all parameters are measured at the same rate within the SR860. The external
frequency, for example, is only measured every reference period (at low frequencies).
The most recent measurements for these parameters are returned by SNAP?
SR860 DSP Lock-in Amplifier