CLASS is a software package for reducing spectroscopic data, and also continuum drifts obtained on a single-dish telescope. CLASS supersedes the older LAS program which was restricted to spectroscopic data.
The originality of CLASS with respect to similar systems already in use is in the way an observation may be identified. In addition to the traditional scan number which can be used to uniquely refer to an observation, the system also enables one to use Selection Criteria as in a data base management system. This faculty, added to a powerful command monitor, SIC , allows easy manipulation of large volumes of data ; the list of observation numbers to be added to get the mean spectrum at one position need no longer be typed in, but may be found by CLASS itself.
CLASS is divided in different parts, called ``Languages'', which have somewhat independent functions (*). Language LAS contains all the general utility functions to handle the data structure, plot the spectra or drifts and calibrate them. Language ANALYSE contains functions to analyse calibrated spectra in more detail. Language GTVL includes commands for basic graphic actions performed by the graphic library used by CLASS ; the same library is used by GreG .
On a standard installation, CLASS is entered by just typing CLASS. In addition to this manual, the reader should consult the SIC manual, and for further processing, the GILDAS and GreG manuals.