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FITS Binary Table Proposals

The FITS Working Group officially approved these 2 proposals in April 2005.

Proposal 1: Recommendation to Incorporate the "Variable-Length Array" Facility in Binary Tables into the FITS Standard

The "Variable-Length Array" FITS data format that is described in Appendix B.1 of the FITS Standard is now used by a number of major data analysis packages. Examples of current usage include the "Redistribution Matrix Files" (RMF), widely used in X-ray astronomy to store calibration information, and the pixel mask files used in the IRAF system. Many of the general software libraries for reading and writing FITS files that are documented on the FITS Support Office web site currently support this variable-length array format in FITS binary tables.

Appendix B.1 is not an official part of the FITS Standard and is included in that document for informational purposes only. Because the implementations described above have now demonstrated the usefulness and importance of the Variable-Length Array Facility, it is recommended that Appendix B.1 be officially approved and incorporated into a new section number 8.3.5 of the FITS Standard, with the editorial changes shown in the draft PDF document. (Also available: a marked-up draft showing the changes from the current wording).

In addition, the following modifications to 3 sections of the FITS Standard are proposed to clarify the use of variable-length arrays:

Finally, the current references to Appendix B.1 in the FITS Standard need to be replaced with references to the new section 8.3.5:

Proposal 2: Recommendation to Incorporate the "Multidimensional Array" Convention in Binary Tables into the FITS Standard

Appendix B.2 in the FITS Standard describes a "Multidimensional array" convention that uses the TDIMn keyword to define the dimensionality of arrays that are contained in binary table columns. Many FITS files now use this convention and contain the TDIMn keyword. Appendix B.2 is currently not an official part of the FITS Standard and is included in that document for informational purposes only. The widespread usage of the TDIMn keyword demonstrates the usefulness and importance of this convention, and thus it is recommended that the "Multidimensional array" convention described in Appendix B.2 be officially approved and incorporated into the definition of the TDIMn keyword in section 8.3.2 of FITS Standard with the editorial changes shown in the draft PDF document. (Also available: a marked-up draft showing the changes from the current wording).

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Last revised: Thursday, 13-Oct-2005 14:33:23 EDT
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