This issue of the NASA/Science Office of Standards and Technology (NOST) News will provide a status of documents this office has been working on for the Consultative Committee for Space Data Systems (CCSDS) and the International Organization for Standardization (ISO).
NOST was involved in the development of the five CCSDS Recommendations produced by CCSDS Panel 2. These are as follows.
CCSDS 620.0-B-2 Standard Formatted Data Units - Structure and Construction Rules (Note: See also Technical Corrigendum 1, November 1996) May 1992 ISO 12175:1994 CCSDS 630.0-B-1 Standard Formatted Data Units - Control Authority Procedures June 1993 ISO 13764:1996 CCSDS 632.0-B-1 Standard Formatted Data Units - Control Authority Data Structures November 1994 ISO/DIS 15395 CCSDS 641.0-B-1 Parameter Value Language Specification (CCSD0006) May 1992 ISO/FDIS 14961 CCSDS 643.0-B-1 ASCII Encoded English November 1992 ISO/FDIS 14962
As is evident from the table, CCSDS Recommendations are normally forwarded to ISO where they are adopted as international standards that may be used in domains other than just the space community. Readers may also note that the Standard Formatted Data Units (SFDU) Control Authority Procedures book has recently become an ISO standard. The Parameter Value Language (PVL) Specification and the ASCII Encoded English Recommendations have now become final draft international standards. This fact indicates that they will shortly be released as ISO standards.
ISO and CCSDS procedures require that their standards be re-examined every five years to ensure that they remain relevant. This coming year NOST will participate in reviewing three documents. ASCII Encoded English will likely be reaffirmed without any changes. However, SFDU - Structure and Construction Rules will likely be extended to support new features such as extension of the class definitions to provide better support for data types such as software and processing rules. Staff also anticipates the definition of compound structures that allow uniform ways of linking multiple data structures together in a variety of ways. The PVL Specification will also be updated to clarify some sections and possibly to extend the language features. NOST is very interested in hearing any suggestions readers have for updates to these documents. Readers who have suggestions for updates or are interested in participating in the update process should contact NOST.
Besides the Recommendations or Blue Books CCSDS produces Draft Recommendations also known as Red Books and Reports also known as Green Books. CCSDS Panel 2 currently has produced five Reports and is actively working on three Draft Recommendations.
Readers are reminded that they can access copies of any approved CCSDS Recommendation or Report by accessing the CCSDS Publication World Wide Web (WWW) page at http://bolero.gsfc.nasa.gov/ccsds/ccsds_publications.html. Draft versions of CCSDS recommendations are not yet integrated into this Web site. Until the draft versions are made available there, electronic versions are generally available, and information on how to access those versions is available from NOST.
There are three Draft Recommendations and another important document that have not yet reached Red Book status. These are as follows.
CCSDS 622.0-R-1 Standard Formatted Data Units - Referencing Environment November 1995 CCSDS 644.0-R-1 The Data Description Language EAST Specification November 1995 CCSDS 647.0-R-1 Data Entity Dictionary Specification Language (DEDSL)(CCSD0011/CCSD0012) November 1996 Open Archival Information System Reference Model January 1997
The SFDU - Referencing Environment Red Book defines "file pointer" mechanisms that can be embedded into other data structures including SFDU data structures. These "file pointer" mechanisms can be used when there is a need to link the internals of a file with other files (such as actual data records and the associated files providing information about the data records) when transferring such collections across computer systems or when storing them for future use. During the formal review of the SFDU - Referencing Environment Red Book (draft standard), only a few minor editorial updates were suggested. These updates were all approved by CCSDS Panel 2, which is now petitioning the CCSDS Management Council to release this document as a Blue Book (approved standard).
Since it is clear that no single data format will be universally accepted, the EAST Specification Red Book addresses the problem of documenting data structures in a computer interpretable manner. The EAST Specification addresses problems such as the variety of operating systems or sensor environments generating a variety of data formats, the need for better understanding of the information by all users, and incomplete or ambiguous documentation. The review by NASA and other space agencies has resulted in a number of suggested improvements to the EAST Specification and its associated tutorials. These updates are in progress.
The Data Entity Dictionary Specification Language (DEDSL) Red Book is currently undergoing formal reviews by the member agencies of CCSDS. These reviews will be completed by the end of April 1997. To form a NASA position, review comments must be submitted to NOST by the end of March 1997. DEDSL defines a language for specifying data dictionaries. This document does not define a data dictionary to be used in all situations. Rather, it provides a model and a language that can be used to define individual dictionaries in a standardized way. A comment form and the current draft are available at http://ad05.atsc.allied.com/CCSDS_review/GRP9613.html.
Although the Archive Reference Model document has not yet reached the stage of a draft that requires formal agency review, NOST has been soliciting comments on the document as it develops. The process of developing this document has been very open with all relevant material (including draft copies of the document) made available on the WWW starting at http://bolero.gsfc.nasa.gov/nost/isoas/.
The development process for the archiving standards is a new one in which NOST is trying to develop the CCSDS Recommendation and ISO Standard concurrently. Hopefully, this new process will eliminate the delay of first completing a CCSDS Recommendation and then needing to go through an additional review period before becoming an ISO Standard. This new process also encourages earlier involvement of commercial vendors as well as involvement of a wider range of educational and governmental organizations. These process improvements should result in quicker adoption and commercialization of these standards.
Readers who are interested in participating in this activity may fill out the form at http://bolero.gsfc.nasa.gov/nost/isoas/us/registration_form.html. Readers who are unable to access the WWW form can respond by E-mail to Donald Sawyer. NOST encourages participation in the U.S. efforts by all interested parties.
Since the last newsletter the Sixth U.S. ISO Archive Standards workshop was held on January 8, 1997, at the National Archives and Records Administration's Archives II facility in College Park, Maryland. Full information on that meeting is available at http://bolero.gsfc.nasa.gov/nost/isoas/us06/ws.html.
NOST has tentatively scheduled several future Workshops on ISO Data Archiving Standards.
Meeting Date Meeting April 9-10, 1997 Seventh U.S. Data Archiving Workshop May 12-14, 1997 Fourth International Data Archiving Workshop Late June or early July 1997 Eighth U.S. Data Archiving Workshop
For more information on any of these documents or meetings, please contact NOST.
Greenbelt, MD 20771
Telephone: John Garrett, +1.301.286.3575
Telephone: Donald Sawyer, +1.301.286.2748
Erin D. Gardner, firstname.lastname@example.org, (301) 286-0163
Hughes STX, Code 633, NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.