[wfc] CHECKSUM Proposal

[William Pence]

Eric Greisen wrote:
> 
>      We can vote on only one paper.  I am voting NO on the 7-page
> paper on which we were asked to vote because it is not in a shape to
> stand on its own.  I suspect that around 1-2 pages of introduction
> and practical usage hints would be enough to fill it out.  I went back
> to the NOST FITS Glossary and was still confused about the meaning of
> HDU - one sentence to clarify the question I asked would avoid the
> whole issue.

First, improving the definition of HDU in the proposal is no problem. We
will do that.  We're just surprised that such a basic term that is used
throughout the Standard (e.g., in sections 4.1, 4.2) should need any
clarification.

The more fundamental issue you raise is in what form must a proposal be
submitted.  One opinion is that is should be in the form of a completely
stand alone document, preferably in a style suitable for publication in
A&A.  But as Don Wells has stated, this is not a requirement. Instead, we
are following the precedent of the Floating Point and Y2000 agreements and
are proposing a specific and relatively small change to the FITS Standard,
namely to incorporate the definition of the CHECKSUM and DATASUM keywords as
defined in our proposal.  Our proposal should be viewed in the context of
the FITS Standard and not in isolation.  As such, our proposal is written in
the same concise, technical style as the FITS Standard.  This was done
deliberately so that it should be very easy to insert our proposal into the
Standard, almost verbatim.  There is little introduction and no practical
usage section in our proposal because the FITS Standard by and large does
not include that type of information.  Even major topics such as ASCII Table
extensions and binary table extensions are presented in Chapter 8 of the
Standard without the slightest bit of introduction or overview.

Part of the difficulty here may be that there has never been a precise
statement of what it is that the WFC is being asked to vote on.  I would
state the current motion as follows:

"It is moved that the definitions of the CHECKSUM and DATASUM keywords, as
stated in the "FITS Checksum Proposal" dated 27 February 2002" be added to
the FITS Standard".

When viewed in this context, I believe our current proposal, with the
addition of a sentence defining "HDU", is in the correct form, and contains
everything that is needed and nothing more.  Still, we are open to
suggestions for improving the wording of the proposal.

Bill Pence