Mandatory Global Attributes

[Ray Osborn]

The US has woken up now, so the next wave of arguments can begin.

Chris wrote:
>At the risk of being pedantic, I think it's worth saying that when Freddie
>asked me if there was a list of global attributes somewhere I looked at the
>summary of the SoftNeSS'96 meeting and got them from paragraph (8) where it
>says
>
>	"Each NeXus file will have the following global attributes:"
>
>which seems like a fairly mandatory definition!
>
I think that that was me being imprecise.  I was defining the global
attributes that exist, not those that have to be included at all costs.
There is a philosophical question here.  We want the NeXus format to be
helpful to people, not a chore to wear them down.  If we insisted on
including people's telephone numbers, we are requiring everyone who writes
a NeXus file to put in a mechanism for finding that out.  Not even ISIS raw
files store user telephone numbers, so every NeXus program would have to
inquire what their phone number was.  This might seem like an invasion of
privacy - in America, people would assume we are going to sell those phone
numbers to telemarketers.

>Trying to remember the discussion I think it centred around the need to have
>some fixed/guaranteed attributes which would be very easy to locate and could
>easily be dragged out of ANY NeXus file. Probably to put in an index file, a
>database or used by a searching program to identify misnamed files (this we
>have had to do before with ISIS raw files when problems have caused them
>to be
>misnamed).
>

I think Przemek had the right idea, that we make mandatory those things
that the API can find out automatically, like the original file name, its
creation date and the NeXus version number.  These can be generated without
bothering the user.  I still strongly urge that we go back to the simpler
NXopen.

Ray

------------------------------------------------------
Dr Ray Osborn                  Tel: +1 (630) 252-9011
Materials Science Division     Fax: +1 (630) 252-7777
Argonne National Laboratory    E-mail: ROsborn at anl.gov
Argonne, IL 60439-4845


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