[iaufwg] convention or standard

[Don Wells]

William Pence wrote:
> .. someone might create a new 'TELEMETRY' extension type to record the 
> raw stream of spacecraft telemetry bytes..

A historical note

The various space agencies around the world receive telemetry from a 
wide variety of spacecraft, and apparently it is not uncommon to forward 
telemetry from agency to agency and site to site, and to store the 
telemetry in various places.  There is lots of this telemetry, so there 
is a management problem as well as the obvious interchange problem.  In 
the 1980s there arose a proposal that telemetry formats should be 
standardized by agreement of the various space agencies of the World.   
In particular, it was proposed that a standard header be prefixed to 
telemetry streams in order to specify ownership/routing and all of the 
other high level metadata that are needed for archival management.   The 
idea came to be known as the Standard Format Data Unit' [SFDU] proposal.

Some people in NASA in the late 80s attempted to argue that their SFDU 
proposal was the answer to astronomy's data format standards problem.   
I was asked to answer this claim circa 1987-88.   Of course it was easy 
for me to make a convincing case that FITS solved problems for us that 
SFDU could not begin to solve.  I deflected SFDU's threat to astronomy 
standardization by pointing out that, if SFDU really did get implemented 
by NASA, NASA could simply put SFDU wrappers around its FITS files.  
I.e., they could create an object type called 'FITS' for SFDU to transmit.

This was the period just after we had negotiated the Generalized 
Extensions Agreement, and we were approaching the point of making it an 
IAU standard.  My memory is that I also added a joking remark to my 
response to the SFDU proposal.  My memory is that I said something like 
this: "Yes, you (SFDU) can wrap up our data format, but we can declare 
XTENSION='SFDU' and wrap you up too!"  :-)

-Don
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