MIME Sub-type Registrations for Flexible Image Transport System (FITS)
RFC 4047

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Network Working Group                                           S. Allen
Request for Comments: 4047                          UCO/Lick Observatory
Category: Informational                                         D. Wells
                                    National Radio Astronomy Observatory
                                                              April 2005

                    MIME Sub-type Registrations for
                 Flexible Image Transport System (FITS)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document describes the registration of the Multipurpose Internet
   Mail Extensions (MIME) sub-types to be used by the international
   astronomical community for the interchange of Flexible Image
   Transport System (FITS) files.  The encoding is defined by the
   published FITS standard documents.  The FITS format has been in use
   since 1979, and almost all data from astronomical observations are
   interchanged by using FITS.

Table of Contents

   1.  Introduction..................................................  2
   2.  Conventions Used in this Document.............................  2
   3.  Overview......................................................  2
   4.  FITS Definition...............................................  3
       4.1.  FITS Structure..........................................  3
       4.2.  History of FITS Features................................  5
       4.3.  Stability of the FITS definition........................  6
       4.4.  Portability of FITS files...............................  7
       4.5.  Application Programming Interfaces to FITS..............  7
       4.6.  FITS File Conformance Testing...........................  8
       4.7.  Archives That Distribute FITS Files.....................  8
   5.  IANA Considerations...........................................  9
       5.1.  Registration of application/fits........................ 10
       5.2.  Registration of image/fits.............................. 14
   6.  References.................................................... 19
       6.1.  Normative References.................................... 19

Allen & Wells                Informational                      [Page 1]
RFC 4047          MIME Sub-type Registrations for FITS        April 2005

       6.2.  Informative References.................................. 20
   7.  Security Considerations....................................... 21
   8.  Contributors.................................................. 21
   9.  Acknowledgements.............................................. 22
   Authors' Addresses................................................ 22
   Full Copyright Statement.......................................... 23

1.  Introduction

   The FITS file format [FITS] was designed in order to facilitate the
   interchange of astronomical image data between observatories.  FITS
   provides a means of transporting arrays and tables of data and
   keyword/value pairs of metadata.  FITS is defined by standards
   documents that are approved by the International Astronomical Union
   (IAU, http://www.iau.org/) and published in refereed journals.

   Before the inception of HTTP, astronomers used the Internet to
   exchange FITS files.  Multiple unofficial media types for FITS files
   [ASU] came into use shortly after the inception of the WWW and have
   remained in use.  Currently (2005) the international astronomical
   community is pursuing many cooperative efforts (e.g., [IVOA], [NVO],
   [AstroGrid], [AVO]) to produce web services that provide astronomical
   data.  The exchange of FITS files is a fundamental element of the
   prototypes for these web services [SIAP].  The astronomical community
   has to agree to use one set of media types for FITS files in order to
   promote interoperability of its various services.

   In its simplest form, FITS is used as a means of transporting
   astronomical image data in a raster form along with coordinate
   information and other standard and locally defined metadata.  In such
   applications FITS is much like the well-known TIFF format [TIFF] with
   the addition of the GeoTIFF tags [GeoTIFF].  However, FITS is capable
   of describing a much broader range of data than 2-dimensional
   rasters.  A consensus has developed in the FITS community that two
   media types are needed:  one for images and one for all other cases.

2.  Conventions Used in this Document

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 [Require].

3.  Overview

   This document describes the registration of the MIME media sub-types
   "application/fits" and "image/fits".