Index: rfcFITS.txt =================================================================== RCS file: /home/cvsroot/fits/mime/rfcFITS.txt,v retrieving revision 1.84 retrieving revision 1.105 diff -b -w -r1.84 -r1.105 3,4c3 < $Id: rfcFITS.txt,v 1.84 2004/03/30 18:58:17 sla Exp $ < Revised by Don Wells at Mon Mar 29 17:33:48 EST 2004 --- > $Id: rfcFITS.txt,v 1.105 2004/08/26 08:25:16 sla Exp $ 7,31c6,7 < - The approval of the IAUFWG mentioned in section 3 has not yet been < requested pending final review of this draft. < < Issues: < - Section 5.2 currently allows 'image/fits' to be used for null < PHDUs (NAXIS=0 or NAXISn=0) or NAXIS>=4 images in 'rare cases'; < these exceptions are controversial, and we may want to delete them. < - Several reviewers have raised the question of whether files with < null PHDUs and IMAGE extensions should be allowed as 'image/fits'. < - The data archives list in Sect.4.7 is in a quasi-random order; < perhaps the list should be ordered by wavelength or by frequency. < The goal for the list is not completeness, but rather a sampling < that demonstrates the full range of usage of FITS (international, < science discipline, wavelength, ground/space, etc). < < Checklist: < - set IETF filename at top of p.1 < - set copyright year '2003' on p.1 < - set expiration date '2003-12-xx'on pp.1 & 20 < - set version date '2003-06-xx' on each page < - verify sequential page numbers 1:N < - verify correct page numbers in Table of Contents on p.2 < - verify that all URLs are currently valid < - verify 72 chars/line, 58 lines/page, 2 blanks at top < - untabify --- > - The approval of the IAUFWG mentioned in section 3 was received > by a vote announced on 2004-08-09. 34c10 < ???draft-allen-fitsmime-00.txt??? UCO/Lick Observatory --- > draft-allen-fitsmime-00.txt UCO/Lick Observatory 37c13 < Expires: 2003-12-xx 2003-06-xx --- > Expires: 2005-02-26 2004-08-26 43,45c19,26 < This document is an Internet-Draft and is subject to all provisions < of Section 10 of RFC2026 except that the right to produce derivative < works is not granted. --- > By submitting this Internet-Draft, I certify that any applicable > patent or other IPR claims of which I am aware have been disclosed, > or will be disclosed, and any of which I become aware will be > disclosed, in accordance with RFC 3668. > > This document may not be modified, and derivative works of it may not > be created, except to publish it as an RFC and to translate it into > languages other than English. 55c36 < material or to cite them other than as "work in progress." --- > material or to cite them other than a "work in progress." 69c50 < Copyright (C) The Internet Society (2003). All Rights Reserved. --- > Copyright (C) The Internet Society (2004). All Rights Reserved. 85,88d65 < < < < 91c68 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 105c82 < 4.7 Archives That Distribute FITS Files..........................8 --- > 4.7 Archives That Distribute FITS Files..........................9 121,122c98,99 < interchange of astronomical image data between observatories. < FITS provides a means of transporting arrays and tables of data and --- > interchange of astronomical image data between observatories. FITS > provides a means of transporting arrays and tables of data and 146a124 > 149c127 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 160,161c138,139 < This document describes the registration of the MIME media < sub-types "application/fits" and "image/fits". --- > This document describes the registration of the MIME media sub-types > "application/fits" and "image/fits". 173,176c151,156 < FITS files are proposed by interested parties, negotiated and reviewed < by ad hoc committees of the FITS community, and approved by national < committess and the IAUFWG and published as an ongoing series of papers < [WCS1, WCS2]. --- > FITS files are proposed by interested parties and negotiated and > reviewed by ad hoc committees of the FITS community. If such usage > of additional keywords is approved by national committees and the > IAUFWG then they become new reserved keywords in the FITS standard > and are published in an ongoing series of papers (e.g., [WCS1, > WCS2]). 204,205d183 < < 208c186 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 215,227c193,205 < space. In particular, the control codes CR, LF, FF, TAB and NUL are not < used in FITS headers. The keywords are up to 8 characters in length. < Some keywords are mandatory, and their meaning is rigidly prescribed. < Among these are keywords that describe the structure and size of the < subsequent data array. The standard reserves other keywords for the < purpose of conveying specifically defined items of metadata. < Keywords that are neither mandatory nor reserved may be inserted < with semantics that are defined by local conventions. (Some local < conventions have later been adopted into standardized practice.) The < end of the header is signified by a block containing the keyword < "END". A simple example of a FITS header for a digital image, using < only keywords that were specified in the initial FITS Agreement of < March 1979 [FITS], is: --- > space. In particular, the control codes CR, LF, FF, TAB and NUL are > not used in FITS headers. The keywords are up to 8 characters in > length. Some keywords are mandatory, and their meaning is rigidly > prescribed. Among these are keywords that describe the structure and > size of the subsequent data array. The standard reserves other > keywords for the purpose of conveying specifically defined items of > metadata. Keywords that are neither mandatory nor reserved may be > inserted with semantics that are defined by local conventions. (Some > local conventions have later been adopted into standardized > practice.) The end of the header is signified by a block containing > the keyword "END". A simple example of a FITS header for a digital > image, using only keywords that were specified in the initial FITS > Agreement of March 1979 [FITS], is: 259,261c237,241 < records will be ignored by FITS reading software, but are used here to < specify the precise journal citation for the FITS standard, an item < of information which is important for archiving on timescales of --- > records will be ignored by FITS reading software, but are used here > to specify the precise journal citation for the FITS standard, an > item of information which is important for archiving on timescales of > > 265c245 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 277,280c257,261 < demonstrates how, in addition to the COMMENT records, 60% of the bytes < in keyword=value records in FITS headers are reserved for comments. < Although the simple header example above is contained in only one < FITS block, multi-block FITS headers are commonly interchanged. --- > demonstrates how, in addition to the COMMENT records, 60% of the > bytes in keyword=value records in FITS headers are reserved for > comments. Although the simple header example above is contained in > only one FITS block, multi-block FITS headers are commonly > interchanged. 319a301 > 322c304 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 363,364c345,346 < of FITS, the FITS community adopted the guiding principle "Once FITS, always < FITS". Under this rule no change may be made to FITS which --- > of FITS, the FITS community adopted the guiding principle "Once FITS, > always FITS". Under this rule no change may be made to FITS which 377a360 > 380c363 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 388,392c371,375 < The first FITS files were written by a PL/I program on an IBM < 360 under OS/MFT (32-bit, twos-complement numbers and 8-bit < EBCDIC characters) and were read by a Fortran program executing < on a CDC 6400 under SCOPE (60-bit, ones-complement numbers and < 6-bit "Display Code" characters).[Remark] --- > The first FITS files were written by a PL/I program on an IBM 360 > under OS/MFT (32-bit, twos-complement numbers and 8-bit EBCDIC > characters) and were read by a Fortran program executing on a CDC > 6400 under SCOPE (60-bit, ones-complement numbers and 6-bit > "Display Code" characters).[Remark] 435a419 > 438c422 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 445,447c429,431 < programming interfaces (APIs) which simplify the task of < manipulating FITS files. Interfaces exist for many languages and < operating systems. A partial list of APIs follows: --- > programming interfaces (APIs) which simplify the task of manipulating > FITS files. Interfaces exist for many languages and operating > systems. A partial list of APIs follows: 478,482c462,467 < in the form of executable binary files for Solaris, Linux, and Windows < platforms, as well as in source code. Although 'fitsverify' has not < been endorsed by the IAUFWG, users should be aware that the designer < of the program was the Secretary of the Technical Panel which < produced the published FITS standard [NOST]. --- > in the form of executable binary files for Solaris, Linux, and > Windows platforms, as well as in source code. Although 'fitsverify' > has not been endorsed by the IAUFWG, users should be aware that the > designer of the program was the Secretary of the Technical Panel > which produced the published FITS standard [NOST]. > 496c481 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 503,504c488,492 < stability of the FITS standard. Examples of such archives associated < with major telescope facilities include: --- > stability of the FITS standard. There are numerous publicly > available archives of FITS files derived from both space and > ground-based observations that span the entire range of the > electromagnetic spectrum from radio to gamma-ray wavelengths. > Examples of such archives, in no particular order, include: 523c511,512 < HIPASS http://www.atnf.csiro.au/research/multibeam/multibeam.html --- > HIPASS http://www.atnf.csiro.au/research/multibeam/ > multibeam.html 527c516,517 < Gemini http://gemini.ast.cam.ac.uk//sciops/data/dataIndex.html --- > Gemini http://gemini.ast.cam.ac.uk/sciops/data/dataIndex.html > XMM-Newton http://xmm.vilspa.esa.es/external/xmm_data_acc/xsa/ 540,541c530,543 < standard described by the original FITS standard paper [FITS]. We < note that the media type "image/gif" [MIME2] admits raster images --- > standard described by the original FITS standard paper [FITS]. > > > > > > > > Allen & Wells Informational [Page 9] > > Internet-Draft MIME types for FITS 2004-08-26 > > > We note that the media type "image/gif" [MIME2] admits raster images 552,556d553 < Allen & Wells Informational [Page 9] < < Internet-Draft MIME types for FITS 2003-06-xx < < 560,561c557 < Subject: Registration of Standard MIME Media type < application/fits --- > Subject: Registration of Standard MIME Media type application/fits 573,575c569,571 < FITS files can be quite large. When transferred via HTTP it < will be common for the transaction to make use of content-coding < or transfer-coding values of "gzip", "compress", or "deflate". --- > FITS files can be quite large. When transferred via HTTP it may be > efficient for the transaction to make use of content-coding or > transfer-coding values such as "gzip", "compress", or "deflate". 579,602c575,591 < FITS provides a means of transporting arrays and tables of data < and keyword/value pairs of metadata. The standard FITS keywords < are either mandatory or reserved. Mandatory keywords provide < information necessary for correct interpretation of the data; < reserved keywords merely provide standard bits of metadata. As < such, the current standard FITS keywords do not pose security < risks. < < A FITS file author may insert additional keywords with semantics < that are not described by the standard. Parties exchanging FITS < files may employ locally defined conventions that use various < keywords and their values to induce actions on the part of the < recipient. There are existing local conventions where such < keywords are used to request the reading of other files and/or < URIs. There are other local conventions where such keywords are < used to modify the state of a telescope and/or instrument. The < security implications of local conventions such as these SHOULD < be analyzed by the parties employing them. < < [Hanisch: Add comment that so far as is known, FITS files have < never been used to transport executable code or as hosts for < viruses, etc.?] < < Interoperability considerations: --- > FITS provides a means of transporting arrays and tables of data and > keyword/value pairs of metadata. The standard FITS keywords are > either mandatory or reserved. Mandatory keywords provide information > necessary for correct interpretation of the data; reserved keywords > merely provide standard bits of metadata. As such, the current > standard FITS keywords do not pose security risks. > > A FITS file author may insert additional keywords with semantics that > are not described by the standard. Parties exchanging FITS files may > employ locally defined conventions that use various keywords and > their values to induce actions on the part of the recipient. There > are existing local conventions where such keywords are used to > request the reading of other files and/or URIs. There are other > local conventions where such keywords are used to modify the state of > a telescope and/or instrument. The security implications of local > conventions such as these SHOULD be analyzed by the parties employing > them. 604,607d592 < FITS files have been successfully transported between wildly < different computers since 1979. The difficulty most likely to < be encountered by a FITS application is inability to acquire the < computational resources required by a very large FITS file. 611a597 > Allen & Wells Informational [Page 10] 612a599 > Internet-Draft MIME types for FITS 2004-08-26 614d600 < Allen & Wells Informational [Page 10] 616c602 < Internet-Draft MIME types for FITS 2003-06-xx --- > Interoperability considerations: 617a604,607 > FITS files have been successfully transported between wildly > different computers since 1979. The difficulty most likely to be > encountered by a FITS application is inability to acquire the > computational resources required by a very large FITS file. 621,622c611,612 < The specification for this content type is published as a series < of papers in refereed astronomical journals: --- > The specification for this content type is published as a series of > papers in refereed astronomical journals: 627,629c617,618 < Greisen, E. and M. Calabretta, "Representations of world < coordinates in FITS", Astronomy & Astrophysics, 395, p. 1061, < 2002. --- > Greisen, E. and M. Calabretta, "Representations of world coordinates > in FITS", Astronomy & Astrophysics, 395, p. 1061, 2002. 632,633c621 < coordinates in FITS", Astronomy & Astrophysics, 395, p. 1077, < 2002. --- > coordinates in FITS", Astronomy & Astrophysics, 395, p. 1077, 2002. 650c638 < ESO-MIDAS http://www.eso.org/projects/esomidas/ --- > MIDAS http://www.eso.org/projects/esomidas/ 664,672c652,654 < At the present time many of these applications are not designed < to support use as viewers of 'application/fits' files in < association with web browsers. < < Additional information: < < A FITS file described with the media type "application/fits" < SHOULD conform to the published standards for FITS files as < determined by convention and agreement within the international --- > At the present time many of these applications are not designed to > support use as viewers of 'application/fits' files in association > with web browsers. 676,679c658 < Internet-Draft MIME types for FITS 2003-06-xx < < FITS community. No other constraints are placed on the content of < a file described as "application/fits". --- > Internet-Draft MIME types for FITS 2004-08-26 681,694d659 < A FITS file described with the media type "application/fits" may < have an arbitrary number of conforming extension header and data < units (XHDUs) that follow its mandatory primary header and data < unit (PHDU). The PHDU may contain zero or more dimensions with < zero or more pixels along each dimension. The XHDUs may be one of < the standard types ("IMAGE", "TABLE", and "BINTABLE") or any other < type that satisfies the 'Requirements for Conforming Extensions' < (section 4.4.1 of [NOST]). < < The PHDU may use the random groups convention, in which the < dimension of the first axis is zero and the keywords GROUPS, < PCOUNT and GCOUNT appear in the header. NAXIS1=0 and GROUPS=T is < the signature of random groups; see section 7 of the Definition of < FITS paper [NOST]. 696c661 < Recommendations for application writers: --- > Additional information: 698,701c663,681 < An application intended to handle "application/fits" SHOULD be < able to provide a user with a manifest of all of the HDUs that are < present in the file and with all of the keyword/value pairs from < each of the HDUs. --- > A FITS file described with the media type "application/fits" SHOULD > conform to the published standards for FITS files as determined by > convention and agreement within the international FITS community. No > other constraints are placed on the content of a file described as > "application/fits". > > A FITS file described with the media type "application/fits" may have > an arbitrary number of conforming extension header and data units > (XHDUs) that follow its mandatory primary header and data unit > (PHDU). The XHDUs may be one of the standard types ("IMAGE", > "TABLE", and "BINTABLE") or any other type that satisfies the > 'Requirements for Conforming Extensions' (section 4.4.1 of [NOST]). > The PHDU or any "IMAGE" XHDU may contain zero to 999 dimensions with > zero or more pixels along each dimension. > > The PHDU may use the random groups convention, in which the dimension > of the first axis is zero and the keywords GROUPS, PCOUNT and GCOUNT > appear in the header. NAXIS1=0 and GROUPS=T is the signature of > random groups; see section 7 of the Definition of FITS paper [NOST]. 703,705c683 < An application intended to handle "application/fits" SHOULD be < prepared to encounter HDUs that have data arrays with < dimensionality ranging from 0 to 999. --- > Recommendations for application writers: 707,709c685,688 < An application intended to handle "application/fits" SHOULD be < prepared to encounter HDUs containing the random groups structure < defined by the standard. --- > An application intended to handle "application/fits" SHOULD be able > to provide a user with a manifest of all of the HDUs that are present > in the file and with all of the keyword/value pairs from each of the > HDUs. 715,718c694,701 < Complete interpretation of the meaning and intended use of the < data in each of the HDUs typically requires the use of heuristics < that attempt to ascertain which local conventions were used by the < author of the FITS file. --- > An application which can modify FITS files or retrieve FITS files > from an external service SHOULD be capable of writing such files to a > local storage medium. > > Complete interpretation of the meaning and intended use of the data > in each of the HDUs typically requires the use of heuristics that > attempt to ascertain which local conventions were used by the author > of the FITS file. 720,721c703,704 < As examples, files with media type "application/fits" might < contain any of the following contents: --- > As examples, files with media type "application/fits" might contain > any of the following contents: 723,724c706,707 < - An empty PHDU (containing zero data elements) followed by a < table HDU that contains a catalog of celestial objects. --- > - An empty PHDU (containing zero data elements) followed by a table > HDU that contains a catalog of celestial objects. 726,727c709,710 < - An empty PHDU followed by a table HDU that encodes a series < of time-tagged photon events from an exposure using an X-ray --- > - An empty PHDU followed by a table HDU that encodes a series of > time-tagged photon events from an exposure using an X-ray 729a713,714 > > 732c717 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 735,736c720,721 < - An empty PHDU followed by a series of IMAGE HDUs containing < data from an exposure taken by a mosaic of CCD detectors. --- > - An empty PHDU followed by a series of IMAGE HDUs containing data > from an exposure taken by a mosaic of CCD detectors. 738,739c723,724 < - An empty PHDU followed by a series of table HDUs that contain < a snapshot of the state of a relational database. --- > - An empty PHDU followed by a series of table HDUs that contain a > snapshot of the state of a relational database. 741,742c726,727 < - A PHDU containing a single image along with keyword/value < pairs of metadata. --- > - A PHDU containing a single image along with keyword/value pairs > of metadata. 744,745c729,730 < - A PHDU with NAXIS1=0 and GROUPS=T followed by random groups < data records of complex fringe visibilities --- > - A PHDU with NAXIS1=0 and GROUPS=T followed by random groups data > records of complex fringe visibilities 750,755c735,740 < contributed database entries for the magic number file which is < used by the Unix "file" command. Magic number files with these < entries are distributed with a variety of Unix-like operating < systems. In addition to recognizing a FITS file using the string < given above, the Uphoff entries also recognize the data type of < the pixels in the PHDU. --- > contributed database entries for the magic number file which is used > by the Unix "file" command. Magic number files with these entries > are distributed with a variety of Unix-like operating systems. In > addition to recognizing a FITS file using the string given above, the > Uphoff entries also recognize the data type of the pixels in the > PHDU. 762,772c747,757 < exchanged via magnetic tape; it does not prescribe any < nomenclature for files on disk. Various sites within the FITS < community have long-established practices where files are presumed < to be FITS by context. File extensions used at such sites < commonly indicate content of the file instead of the data format. < < In the absence of other information it is reasonably safe to < presume that a file name ending in ".fits" is intended to be a < FITS file. Nevertheless, there are other commonly used < extensions; e.g., ".fit", ".fts", and many others not suitable for < listing in a media type registration. --- > exchanged via magnetic tape; it does not prescribe any nomenclature > for files on disk. Various sites within the FITS community have > long-established practices where files are presumed to be FITS by > context. File extensions used at such sites commonly indicate > content of the file instead of the data format. > > In the absence of other information it is reasonably safe to presume > that a file name ending in ".fits" is intended to be a FITS file. > Nevertheless, there are other commonly used extensions; e.g., ".fit", > ".fts", and many others not suitable for listing in a media type > registration. 785,786c770,772 < The IAU FITS Working Group may authorize changes to this < document. --- > The IAU FITS Working Group may authorize changes to this document. > > 790c776 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 796,797c782 < Subject: Registration of Standard MIME Media type < image/fits --- > Subject: Registration of Standard MIME Media type image/fits 809,811c794,796 < FITS files can be quite large. When transferred via HTTP it will < be common for the transaction to make use of content-coding or < transfer-coding values of "gzip", "compress", or "deflate". --- > FITS files can be quite large. When transferred via HTTP it may be > efficient for the transaction to make use of content-coding or > transfer-coding values such as "gzip", "compress", or "deflate". 815,832c800,816 < FITS provides a means of transporting arrays and tables of data < and keyword/value pairs of metadata. The standard FITS keywords < are either mandatory or reserved. Mandatory keywords provide < information necessary for correct interpretation of the data; < reserved keywords merely provide standard bits of metadata. As < such, the current standard FITS keywords do not pose security < risks. < < A FITS file author may insert additional keywords with semantics < that are not described by the standard. Parties exchanging FITS < files may employ locally defined conventions that use various < keywords and their values to induce actions on the part of the < recipient. There are existing local conventions where such < keywords are used to request the reading of other files and/or < URIs. There are other local conventions where such keywords are < used to modify the state of a telescope and/or instrument. The < security implications of local conventions such as these SHOULD be < analyzed by the parties employing them. --- > FITS provides a means of transporting arrays and tables of data and > keyword/value pairs of metadata. The standard FITS keywords are > either mandatory or reserved. Mandatory keywords provide information > necessary for correct interpretation of the data; reserved keywords > merely provide standard bits of metadata. As such, the current > standard FITS keywords do not pose security risks. > > A FITS file author may insert additional keywords with semantics that > are not described by the standard. Parties exchanging FITS files may > employ locally defined conventions that use various keywords and > their values to induce actions on the part of the recipient. There > are existing local conventions where such keywords are used to > request the reading of other files and/or URIs. There are other > local conventions where such keywords are used to modify the state of > a telescope and/or instrument. The security implications of local > conventions such as these SHOULD be analyzed by the parties employing > them. 845a830,832 > > > 848c835 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 853,854c840,841 < The specification for this content type is published as a series < of papers in refereed astronomical journals: --- > The specification for this content type is published as a series of > papers in refereed astronomical journals: 880c867 < ESO-MIDAS http://www.eso.org/projects/esomidas/ --- > MIDAS http://www.eso.org/projects/esomidas/ 886c873 < STSDAS http://stsdas.stsci.edu/ --- > STSDAS http://www.stsci.edu/resources/software_hardware/stsdas 891a879 > XMM-SAS http://xmm.vilspa.esa.es/external/xmm_sw_cal/sas_frame.shtml 906c894 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 909c897 < There is also a FITS plug-in for Adobe Photoshop --- > There are also two FITS plug-ins for Adobe Photoshop 911c899,900 < http://astroshed.com/fitsplug/fitsplug.htm --- > http://astroshed.com/fitsplug/fitsplug.htm and > http://www.spacetelescope.org/projects/fits_liberator/ 913,914c902,903 < At the present time many of the applications listed above are < not designed to support use as viewers of 'image/fits' files in --- > At the present time many of the applications listed above are not > designed to support use as viewers of 'image/fits' files in 919,934c908,923 < A FITS file described with the media type "image/fits" SHOULD have < a PHDU with positive integer values for the NAXIS and NAXISn < keywords, and hence SHOULD contain at least one pixel. Files < with 4 or more non-degenerate axes (NAXISn>1) SHOULD be < described as 'application/fits', not as 'image/fits'. (In rare < cases it may be appropriate to describe a NULL image -- a dataless < container for FITS keywords, with NAXIS=0 or NAXISn=0 -- or an < image with 4+ non-degenerate axes as < 'image/fits' but this usage is discouraged because such files may < confuse simple image viewer applications.) FITS files declared as < 'image/fits' MAY also have one or more conforming XHDUs following < their PHDUs. These extension HDUs MAY contain standard, < non-linear, world coordinate system (WCS) information in the form < of tables or images. The extension HDUs MAY also contain other, < non-standard metadata pertaining to the image in the PHDU in the < forms of keywords and tables. --- > A FITS file described with the media type "image/fits" SHOULD have a > PHDU with positive integer values for the NAXIS and NAXISn keywords, > and hence SHOULD contain at least one pixel. Files with 4 or more > non-degenerate axes (NAXISn>1) SHOULD be described as > 'application/fits', not as 'image/fits'. (In rare cases it may be > appropriate to describe a NULL image -- a dataless container for FITS > keywords, with NAXIS=0 or NAXISn=0 -- or an image with 4+ > non-degenerate axes as 'image/fits' but this usage is discouraged > because such files may confuse simple image viewer applications.) > > FITS files declared as 'image/fits' MAY also have one or more > conforming XHDUs following their PHDUs. These extension HDUs MAY > contain standard, non-linear, world coordinate system (WCS) > information in the form of tables or images. The extension HDUs MAY > also contain other, non-standard metadata pertaining to the image in > the PHDU in the forms of keywords and tables. 938,941c927,930 < PHDU. This means that "image/fits" SHOULD NOT be applied to < FITS files containing MEF (multi-exposure-frame) mosaic < images. Also, random groups files MUST be described as < 'application/fits' and not as 'image/fits'. --- > PHDU. This means that "image/fits" SHOULD NOT be applied to FITS > files containing MEF (multi-exposure-frame) mosaic images. Also, > random groups files MUST be described as 'application/fits' and not > as 'image/fits'. 943,944c932,933 < A FITS file described with the media type "image/fits" is also < valid as a file of media type "application/fits". The choice of --- > A FITS file described with the media type "image/fits" is also valid > as a file of media type "application/fits". The choice of 949,955c938,946 < An application that is intended to handle "image/fits" SHOULD be < able to provide a user with a manifest of all of the HDUs that are < present in the file and with all of the keyword/value pairs from < each of the HDUs. An application writer MAY choose to ignore HDUs < beyond the PHDU, but even in this case the application SHOULD be < able to present the user with the keyword/value pairs from the < PHDU. --- > An application that is intended to handle "image/fits" SHOULD be able > to provide a user with a manifest of all of the HDUs that are present > in the file and with all of the keyword/value pairs from each of the > HDUs. An application writer MAY choose to ignore HDUs beyond the > PHDU, but even in this case the application SHOULD be able to present > the user with the keyword/value pairs from the PHDU. > > > 957,967d947 < Note that an application intended to render "image/fits" for < viewing by a user has significantly more responsibility than an < application intended to handle, e.g., "image/tiff" or "image/gif". < FITS data arrays contain elements which typically represent the < values of a physical quantity at some coordinate location. < Consequently they need not contain any pixel rendering information < in the form of transfer functions, and there is no mechanism for < color look-up tables. An application SHOULD provide this < functionality, either statically using a more or less < sophisticated algorithm, or interactively allowing a user various < degrees of choice. 973c953 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 975a956,966 > Note that an application intended to render "image/fits" for viewing > by a user has significantly more responsibility than an application > intended to handle, e.g., "image/tiff" or "image/gif". FITS data > arrays contain elements which typically represent the values of a > physical quantity at some coordinate location. Consequently they > need not contain any pixel rendering information in the form of > transfer functions, and there is no mechanism for color look-up > tables. An application SHOULD provide this functionality, either > statically using a more or less sophisticated algorithm, or > interactively allowing a user various degrees of choice. > 977,995c968,984 < floating-point numbers. The dynamic range of the data array < values may exceed that of the display medium and the eye, and < their distribution may be highly nonuniform. Logarithmic, < square-root, and quadratic transfer functions along with histogram < equalization techniques have proved helpful for rendering FITS < data arrays. Some elements of the array may have values which < indicate that their data are undefined or invalid; these should be < rendered distinctly. Via WCS Paper I [WCS1] the standard permits < "CTYPEnnn = 'COMPLEX'" to assert that a data array contains < complex numbers (future revisions might admit other elements such < as quaternions or general tensors). < < Three-dimensional data arrays (NAXIS=3 with NAXIS1, NAXIS2 and < NAXIS3 >1) are of < special interest. Applications intended to handle "image/fits" < MAY default to displaying the first 2D plane of such an image < cube, or they MAY default to presenting such an image in a fashion < akin to that used for an animated GIF, or they MAY present the < data cube as a mosaic of 'thumbnail' images. Even in the absence --- > floating-point numbers. The dynamic range of the data array values > may exceed that of the display medium and the eye, and their > distribution may be highly nonuniform. Logarithmic, square-root, and > quadratic transfer functions along with histogram equalization > techniques have proved helpful for rendering FITS data arrays. Some > elements of the array may have values which indicate that their data > are undefined or invalid; these should be rendered distinctly. Via > WCS Paper I [WCS1] the standard permits "CTYPEnnn = 'COMPLEX'" to > assert that a data array contains complex numbers (future revisions > might admit other elements such as quaternions or general tensors). > > Three-dimensional data arrays (NAXIS=3 with NAXIS1, NAXIS2 and NAXIS3 > > 1) are of special interest. Applications intended to handle > "image/fits" MAY default to displaying the first 2D plane of such an > image cube, or they MAY default to presenting such an image in a > fashion akin to that used for an animated GIF, or they MAY present > the data cube as a mosaic of 'thumbnail' images. Even in the absence 1001,1009c990,1006 < entity such as a spectrum or a time series. Applications intended < to handle "image/fits" MAY default to displaying such an image as < a graphical plot rather than as a two-dimensional picture with a < single row. < < An application that cannot handle an image with dimensionality < other than 2 SHOULD gracefully indicate its limitations to its < users when it encounters NAXIS=1 or NAXIS=3 cases, while still < providing access to the keyword/value pairs. --- > entity such as a spectrum or a time series. Applications intended to > handle "image/fits" MAY default to displaying such an image as a > graphical plot rather than as a two-dimensional picture with a single > row. > > An application that cannot handle an image with dimensionality other > than 2 SHOULD gracefully indicate its limitations to its users when > it encounters NAXIS=1 or NAXIS=3 cases, while still providing access > to the keyword/value pairs. > > > > > > > > 1011,1022d1007 < FITS files with degenerate axes (i.e., one or more NAXISn=1) MAY < be described as 'image/fits', but the first axes SHOULD be < non-degenerate (i.e., the degenerate axes SHOULD be the highest < dimensions). An algorithm designed to render only two-dimensional < images will be capable of displaying such an NAXIS=3 or NAXIS=4 < FITS array that has one or two of the axes consisting of a single < pixel, and an application writer SHOULD consider coding this < capability into the application. Writers of new applications < which generate FITS files intended to be described as 'image/fits' < SHOULD consider using the WCSAXES keyword [WCS1] to declare the < dimensionality of such degenerate axes, so that NAXIS can be used < to convey the number of non-degenerate axes. 1027c1012,1013 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 > 1028a1015,1026 > FITS files with degenerate axes (i.e., one or more NAXISn=1) MAY be > described as 'image/fits', but the first axes SHOULD be > non-degenerate (i.e., the degenerate axes SHOULD be the highest > dimensions). An algorithm designed to render only two-dimensional > images will be capable of displaying such an NAXIS=3 or NAXIS=4 FITS > array that has one or two of the axes consisting of a single pixel, > and an application writer SHOULD consider coding this capability into > the application. Writers of new applications which generate FITS > files intended to be described as 'image/fits' SHOULD consider using > the WCSAXES keyword [WCS1] to declare the dimensionality of such > degenerate axes, so that NAXIS can be used to convey the number of > non-degenerate axes. 1033,1038c1031,1036 < contributed database entries for the magic number file which is < used by the Unix "file" command. Magic number files with these < entries are distributed with a variety of Unix-like operating < systems. In addition to recognizing a FITS file using the string < given above, the Uphoff entries also recognize the data type of < the pixels in the PHDU. --- > contributed database entries for the magic number file which is used > by the Unix "file" command. Magic number files with these entries > are distributed with a variety of Unix-like operating systems. In > addition to recognizing a FITS file using the string given above, the > Uphoff entries also recognize the data type of the pixels in the > PHDU. 1045,1055c1043,1053 < exchanged via magnetic tape; it does not prescribe any < nomenclature for files on disk. Various sites within the FITS < community have long-established practices where files are presumed < to be FITS by context. File extensions used at such sites < commonly indicate content of the file instead of the data format. < < In the absence of other information it is reasonably safe to < presume that a file name ending in ".fits" is intended to be a < FITS file. Nevertheless, there are other commonly used < extensions; e.g., ".fit", ".fts", and many others not suitable for < listing in a media type registration. --- > exchanged via magnetic tape; it does not prescribe any nomenclature > for files on disk. Various sites within the FITS community have > long-established practices where files are presumed to be FITS by > context. File extensions used at such sites commonly indicate > content of the file instead of the data format. > > In the absence of other information it is reasonably safe to presume > that a file name ending in ".fits" is intended to be a FITS file. > Nevertheless, there are other commonly used extensions; e.g., ".fit", > ".fts", and many others not suitable for listing in a media type > registration. 1071,1077d1068 < < < < < < < 1080c1071 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 1135a1127 > 1138c1130 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 1167c1159 < Specification", http://www.us-vo.org/publications.html, --- > Specification", http://www.us-vo.org/pubs/, 1171c1163 < http://partners.adobe.com/asn/developer/pdfs/tn/TIFF6.pdf, --- > http://partners.adobe.com/asn/developer/pdfs/tn/TIFF6.pdf 1193a1186 > 1196c1189 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 1239,1251c1232,1241 < Jeff Uphoff of the National Radio Astronomy Observatory contributed < the FITS entries for the magic number file that permits the Unix-like < "file" command on many systems to identify a FITS file. < < < < < < < < < < --- > Jeff Uphoff of the National Radio Astronomy Observatory (NRAO) > contributed the FITS entries for the magic number file that permits > the Unix-like "file" command on many systems to identify a FITS file. > > Nelson Zarate verified that the fgread and fgwrite programs are > able to store hierarchical directories containing files with > arbitrary MIME media types within a HDU of a FITS file. The fgread > and fgwrite programs are part of the FITSUTIL IRAF external package > written by N. Zarate, D. Tody, R. Seaman at National Optical > Astronomy Observatory (NOAO), 1999-09. 1258c1248 < Internet-Draft MIME types for FITS 2003-06-xx --- > Internet-Draft MIME types for FITS 2004-08-26 1277c1267 < Phone: +1 804 296 0277 --- > Phone: +1 434 296 0277 1282c1272,1300 < Copyright (C) The Internet Society (2003). All Rights Reserved. --- > Copyright (C) The Internet Society (2004). This document is subject > to the rights, licenses and restrictions contained in BCP 78 and > except as set forth therein, the authors retain all their rights. > > This document and the information contained herein are provided on an > "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE > REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE > INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR > IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF > THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED > WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. > > Intellectual Property > > The IETF takes no position regarding the validity or scope of any > Intellectual Property Rights or other rights that might be claimed to > pertain to the implementation or use of the technology described in > this document or the extent to which any license under such rights > might or might not be available; nor does it represent that it has > made any independent effort to identify any such rights. Information > on the procedures with respect to rights in RFC documents can be > found in BCP 78 and BCP 79. > > Copies of IPR disclosures made to the IETF Secretariat and any > assurances of licenses to be made available, or the result of an > attempt made to obtain a general license or permission for the use of > such proprietary rights by implementers or users of this > specification can be obtained from the IETF on-line IPR repository at > http://www.ietf.org/ipr. 1284,1306d1301 < This document and translations of it may be copied and furnished to < others, and derivative works that comment on or otherwise explain it < or assist in its implementation may be prepared, copied, published < and distributed, in whole or in part, without restriction of any < kind, provided that the above copyright notice and this paragraph are < included on all such copies and derivative works. However, this < document itself may not be modified in any way, such as by removing < the copyright notice or references to the Internet Society or other < Internet organizations, except as needed for the purpose of < developing Internet standards in which case the procedures for < copyrights defined in the Internet Standards process must be < followed, or as required to translate it into languages other than < English. < < The limited permissions granted above are perpetual and will not be < revoked by the Internet Society or its successors or assigns. < < This document and the information contained herein is provided on an < "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING < TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING < BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION < HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF < MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1309d1303 < Expires 2003-12-xx 1310a1305 > Allen & Wells Informational [Page 22] 1311a1307 > Internet-Draft MIME types for FITS 2004-08-26 1314c1310,1364 < Allen & Wells Informational [Page 22] --- > The IETF invites any interested party to bring to its attention any > copyrights, patents or patent applications, or other proprietary > rights that may cover technology that may be required to implement > this standard. Please address the information to the IETF at > ietf-ipr@ietf.org. > > Acknowledgement > > Funding for the RFC Editor function is currently provided by the > Internet Society. > > Expires: 2005-02-26 > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Allen & Wells Informational [Page 23]