> Just to clarify things, there are two issues being discussed here:

I thought it was more than two issues.  The other is what to do about 
other tasks that create an NDF ab initio, such as those I mentioned in 
KAPPA, Figaro, and other CONVERT x2NDF tasks.  That's an addendum to
Issue 1).

> 1) Whether  fits2ndf should produce a History component in the output
> NDF that records the fact that fits2ndf has been run (and will also
> record all subsequent processing).
>
> 2) Whether, in addition to 1), fits2ndf should also read any history
> information from the input FITS file and add it into the History
> component of the output NDF.

This hasn't be a priority since (as Tim pointed out) this information 
isn't lost.  The original FITS headers are stored in the FITS airlock
of your NDF, and are visible via KAPPA:FITSLIST.  Yes it would be more 
convenient to just run HISLIST to view the entire history, but 
hitherto it hasn't been flagged as sufficiently important to implement 
it.  One problem is to know how to break up various steps listed in 
HISTORY headers for what is arbitrary text.  We could just lump 
contiguous sets of FITS HISTORY lines as a single NDF HISTORY record.
It's the fact that we don't have the semantics to interpret these 
headers into NDF form is why they're placed in the FITS airlock, just 
like most FITS headers.

>> It is rather "frustrating" to find the
>> HISTORY missing as the only time most people are going to notice it missing
>> is when they explicitly need it. It seem odd to me, again as a user, to have
>> a rather useful bit of functionality turned off by default.

I agree.  As I explained it's historical.  (-:  It's not clear whether 
we have the effort to tackle it properly rather than apply the change 
David made in 1) task by task as demanded.

>> How many fits files actually have HISTORY components? If its "not very many"

Quite a high proportion.  It depends on the institution and the
culture.  It is most common where data are not raw and have been 
manipulated by a data-processing pipeline.  Thus public surveys, space 
and radio data generally have HISTORY.  However, that's not the sole 
use.

Malcolm