HP 8753E Programming And Command Reference Manual page 38

Marker data can be output to a controller by using analyzer commands.
These commands cause the analyzer to transmit three numbers: marker
value 1, marker value 2, and marker stimulus value. For example, in
log-magnitude display mode we get the log magnitude at the marker
(value l), zero (value 2), and the marker frequency. See 'fable l-4 for
a complete listing of all the possibilities for values 1 and 2. The four
possibilities for the marker stimulus value are:
time (as in time domain, Option 010 Only)
n
CW time
n
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