Keywords: class-herschel-fits

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## FITS level

The command `LASFITS` traverses one by one all the HDUs in the FITS file independently of their names. If a binary table is found and:

- if it contains a column `frequency` or `wave`, it is assumed to be a level 2.5 Herschel-HIFI FITS and the specific decoding is started.
- if if contains at least one column `lsbfrequency_*` or `usbfrequency_*`, it is assumed be a level 2.0 Herschel-HIFI FITS and the specific decoding is started.

The levels 2.0 and 2.5 refer to the reduction pipeline level in HCSS. The resulting FITS provides (almost) the same data but under a different form. For our needs, the main differences come from values which are found in columns of the binary table in level 2.0, and in metacards (see below) of the header in level 2.5.