Keywords: class-associated-arrays

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# Implementation details

The ASSOCIATED ARRAYS support was officialy introduced in the oct15 version of CLASS, together with the Herschel-HIFI FITS reader. They are available in a new section (identifier code -19) in the CLASS observation header. The size of this section is variable, as there can be several arrays in the section, and the size of each array is the same as `RY`. The section provides the number of arrays stored, then for each array its description and its data. See Table for details.

Table: Description of the section ASSOCIATED ARRAYS in the CLASS observation header. Each array is described by its format, 2nd dimension, name, and unit. The bad (blanking) value is stored in the same format as the data, then the data array itself follows. Order matters here.
| Name | Format (disk) | Description
Once in the section | `N` | INTEGER*4 | Number of arrays
Repeated per array | `NAME` | CHARACTER*12 | Array name (identifier)
'' | `UNIT` | CHARACTER*12 | Unit (blank if not relevant)
'' | `DIM2` | INTEGER*4 | Second dimension (0 for 1D array)
'' | `FMT` | INTEGER*4 | Data format (internal code)
'' | `BAD` | FMT | Blanking value
'' | DATA | FMT | The data array (Nchan values, times `DIM2`)

A basic example using 2 arrays is shown in Appendix .

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