NOST News

Volume 12, Number 3, September 1996
By John Garrett and Donald Sawyer

The NASA/Science Office of Standards and Technology (NOST) continues to support the development of an International Organization for Standardization (ISO) Archiving Reference Model and subsequent standards by leading a U.S. government, industry, and academia effort that is developing draft material for the Consultative Committee for Space Data Systems (CCSDS) and ISO Technical Committee 20. The need for such a reference model has become apparent to those archives concerned about long-term digital information preservation as they try to learn from one another and as they attempt to communicate with vendors about their needs. The lack of agreement on what is really necessary and terms and the lack of agreement on what is really necessary to preserve digital information hinders archival progress and a recognition of what constitutes a truly world-class archive. The problems of long-term digital information preservation are no longer confined to traditional archives as more and more information lives digitally. For a good study of many of the archival issues, see the recent report Preserving Digital Information from the Task Force on Archiving Digital Information at http://www.rlg.org/ArchTF/.

The Fourth U.S. ISO Archive Standards workshop was held at the Johns Hopkins University Applied Physics Laboratory (APL). This workshop focused on refinement of the draft Archiving Reference Model, Version 5. This version reflects results from the international archiving workshop held at the end of April 1996 and is available from http://bolero.gsfc.nasa.gov/nost/isoas/ref_model.html. Those who have more interest can review the full minutes available at http://bolero.gsfc.nasa.gov/nost/isoas/us04/ws.html. As the model has progressed through several versions of the document, workshop participants have been adding new insights, experiences, and alternatives to help make the model resonate with the experiences of current archive administrators and users. These workshops, open to all U.S. participants, have been successful because of the broad extent of participation.

NOST has scheduled several future U.S. Workshops on ISO Data Archiving Standards. The Fifth U.S. Workshop will be held at the National Archives and Records Administration's Archives II facility in College Park, Maryland. The meeting is set for October 2-3, 1996. Information on this workshop and links to registration forms are available at http://bolero.gsfc.nasa.gov/nost/isoas/us05/ws.html. The Fifth U.S. Workshop will focus on preparing U.S. input for the Third International Workshop being held on November 4-5, 1996. Potential participants in U.S. workshops may also be interested in the tentative dates of these workshops.

    October 2-3, 1996	  Fifth U.S. Data Archiving Workshop
    November 4-5, 1996	  Third International Data Archiving Workshop
    January 15-16, 1997	  Sixth U.S. Data Archiving Workshop
    April 16-17, 1997	  Seventh U.S. Data Archiving Workshop
    May 1997		  Fourth International Data Archiving Workshop
    July 16-17, 1997	  Eighth U.S. Data Archiving Workshop 

NOST encourages participation in the U.S. efforts by all interested parties. Whether interested in just reviewing the resulting documents or in editing and reviewing sections of the documents being produced, interested readers may fill out the form at http://bolero.gsfc.nasa.gov/nost/isoas/us/registration_form.html. Readers who are unable to access the World Wide Web form can respond by E-mail to Donald Sawyer at sawyer@ncf.gsfc.nasa.gov.

Besides the data archiving work NOST remains active in promoting improved standards and codifying existing practices. Within these areas NOST would like to inform the readers of three document reviews: the CCSDS Red Book Review for the Enhanced ADA Subset (EAST), the CCSDS Red Book Review for Standard Formatted Data Unit (SFDU) Referencing Environment, and the review of the new version of the NOST Definition of the Flexible Image Transport System (FITS).

CCSDS Red Books are draft Recommendations circulated for formal review by the member agencies. When the comments received during the Red Book reviews are processed, CCSDS produces a Blue Book, which is a final Recommendation or Standard. These books are then generally forwarded to ISO for adoption as ISO standards. The EAST Red Book review is underway with comments due by November 1, 1996. The SFDU-Referencing Environment Red Book Review will start about September 15, 1996, and comments will be due by November 15, 1996. Copies of CCSDS Red Books and Review forms are available from


NASA GSFC
Aerospace Data Standards Office, Code 730.4
Greenbelt, Maryland 20771
Attn: William B. Poland, Jr.

The EAST document addresses the problem of documenting data structures. There will always be a variety of data structures, typically in the form of records or files, used to hold information. The representation of this information may reflect the influence of various operating systems or the sensor environments that generated them. Thus, the information is not easily understood by all users. A related problem is that the documentation is often incomplete or ambiguous. Not only does that cause problems with immediate usage of the data, but it exacerbates the problem of long-term use and understanding of the information. The EAST Specification defines a language that can be used to describe the information representations of a record or file in a non-ambiguous manner. Based on this description, generic software can be used to access data values. This helps preserve the information content of such data while making its access more cost effective.

The SFDU-Referencing Environment Red Book defines "file pointer" mechanisms that can be embedded into other data structures including SFDU data structures. When transferring collections of files across computer systems, there is a need to link the files in the collections and also to maintain those links to ensure the collections are properly understood. This specification addresses the problem by defining these "file pointer" mechanisms and specifying the syntax to be used. There are four CCSDS-defined environments, each providing a different referencing capability and using a slightly different mechanism.

The NOST FITS Technical Panel will be meeting in mid-September 1996 to review the draft of the NOST Definition of FITS, Version 2. At its meeting it expects to complete a draft for public review. Thus, in late September 1996 interested readers should check the Web pages of the FITS Support Office at http://www.gsfc.nasa.gov/astro/fits/fits_home.html or the FITS Basics Web Page at http://www.gsfc.nasa.gov/astro/fits/basics_info.html to obtain copies of the draft document.

The NOST Definition of FITS, Version 2 incorporates updates such as the IMAGE and BINTABLE extensions, which are currently endorsed by the International Astronomical Union FITS Working Group (IAUFWG) but which are not currently included in Version 1.1. After comments from the public are addressed by the FITS Technical Panel, Version 2 will be submitted for approval as a NOST standard and then for endorsement by the IAUFWG as the international FITS standard. The NOST staff is sure that many readers will be able to use one or more of these standards in the future to save money, time, or effort in their jobs or procurement. NOST looks forward to their comments on these drafts so it can make the resulting standards as useful as possible to the NASA and U.S. science communities.

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Author:Miranda Beall
Curators: Erin Gardner and Miranda Beall
Responsible Official: Dr. Joseph H. King. Code 633
Last Revised: 21 Nov 1996 [EDG]