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2.7 Image Extension

In the late 1980s, there had been some discussion in the FITS community about providing a mechanism for including multidimensional arrays in extensions as well as in the primary data array. The IUE group was looking for a way to include several related arrays in the same file, in particular, both their data and a flag array in which the flag for each element would refer to the data for that element. Because the data types for the flag and the data were different, they could not just add another axis and include the flag data in the primary data array. J. D. Ponz and J. R. Muñoz of the ESA IUE group and R. Thompson (CSC) of the GSFC IUE group made a detailed draft available electronically early in 1992. The extension was given the name IMAGE. The only significant discussion was whether or not to provide for Random Groups records after an image extension; because Random Groups have largely fallen into disuse and are not recommended for future use, the decision was not to allow Random Groups records.