Reads out the bandwidth search result.
The bandwidth search can performed relatively to the marker <Mk>,
or relatively to the absolute maximum value of the trace (in this
case the number of the marker is ignored), what is set by the
CALC:MARK:BWID:REF command.
The data include 4 elements:
<numeric 1> Bandwidth;
<numeric 2> Center frequency;
<numeric 3> Q value;
<numeric 4> Loss;
(query only)
If the bandwidth search is impossible, all the read out values are 0. If the
search is performed relatively to a maker, which is OFF, an error occurs.