## Continuum

So far, we have handled only Spectroscopic data, but Continuum data can be processed by CLASS . Currently, only continuum drifts can be reduced. The basic idea is to treat continuum drifts as spectra would be. Accordingly, very few commands behave differently in Continuum and Spectroscopy modes.

Continuum mode is accessed by typing the SET TYPE CONTINUUM command. The prompt then changes to CAS> (Continuum Analysis System). You can return to Spectroscopy mode later on typing the SET TYPE SPECTROSCOPY or LINE command and the prompt changes to LAS> (Line Analysis System).

Some commands have slightly different behaviour in Spectroscopy and Continuum modes.

- SET UNIT has no effect in Continuum mode.
- SET ANGLE also controls the plotting units in Continuum mode.
- METHOD: only GAUSS and CONTINUUM methods are allowed in Continuum mode.
- LINES has no effect with CONTINUUM method.
- HEADER uses a different format for Continuum and Spectroscopy modes.
- STRIP produces a map from a set of parallel drifts. The index must define such a set of drifts.
- FITS format support is experimental for continuum data.
- With CONTINUUM method, PRINT FIT command only outputs a single component, and the component number is not written.
- SET ALIGN CHANNELS and SET ALIGN POSITION are the only available alignment modes in Continuum mode.

Except for these restrictions, the behaviour of other commands is similar. Note that command FIND only selects data of the current type.