In Spectral mode, CLIC plots spectral data, the subbands L01 to L08, as a function of a frequency variable. Only one spectrum per subband and per scan is available.

Spectral mode is selected whenever the X coordinate is a frequency-like
variable: `SET X I_FREQ, SET X CHANNEL, SET X VELOCITY, SET X SKY_F`
result in spectral mode display.

It is possible to plot Continuum data (C01 to C08) as a function of frequency, but of course, each continuum subband is only ONE frequency point.

Gildas manager 2014-07-01