Subject: Re: Scientific Data Format Information FAQ

From: [email-masked] (William Thompson)
Date: 26 Jan 94 15:22:04 GMT

[email-masked] (Ilana Stern) writes:

>7. PDS

>  In recent years, the Planetary Data System (PDS) has been responsible
>for archiving space mission data on CD-ROM media, using its own self-
>describing data format, variously know as PDS, SFDU (Standard Formatted
                                                ^^^^
>Data Unit), or ODL (Object Description Language).  ...

This is an error--the term SFDU or Standard Formatted Data Unit does not refer
to PDS/ODL files.  Instead, the SFDU mechanism is a way of associating with a
data file a label that serves as a pointer to a description of the file format.
As such, a PDS/ODL file can qualify as an SFDU, but so could files in FITS,
CDF, etc., or even in mission-specific file formats, so long as the format
description is registered.

(I like to think of SFDUs as a "Dewey decimal system" for data files.  :^) )

Information on SFDUs can be obtained from

	CCSDS Secretariat
	Communications and Data Systems Division, (Code-OS)
	National Aeronautics and Space Administration
	Washington, DC 20546, USA

I would like to see information on SFDUs included in the FAQ, but am not
qualified to write it myself.  You might try contacting Don Sawyer at

	NSSDCA::SAWYER
or
	[email-masked]

to see if anyone in his office would be interested in contributing something
about SFDUs for the FAQ.  I myself would be really happy if some of the SFDU
documentation was available online in WWW/HTML format.

Bill Thompson

---

From: [email-masked] (BARRY M. SCHLESINGER)
Date: 28 Jan 1994 17:14 EDT

In article <[email-masked]>, [email-masked] (William Thompson) writes...

>...the SFDU mechanism is a way of associating with a
>...
There is also a control authority structure and procedure for 
registering descriptions.
>documentation was available online in WWW/HTML format.

Don Sawyer and the other major players are on their way (if the ice 
storm didn't mess up their travel) to a CCSDS sponsored meeting on 
SFDU, control authorities, and registration in Japan next week (31 
January - 4 February). Because of the usual pre-meeting rush, 
complicated by facility closings due to weather, they haven't had time 
to answer.   They should have something to say about plans for 
on-line SFDU documentation when they get back.
				Barry Schlesinger
				NOST FITS Support Office.