[fitsbits] start of Public Comment Period on the CHECKSUM convention

[Rob Seaman]

On Jul 5, 2015, at 11:05 AM, THIERRY FORVEILLE <thierry.forveille at ujf-grenoble.fr> wrote:
>> From: "Erik Bray" <embray at stsci.edu>
>> 
>> On 07/02/2015 06:14 AM, Mark Calabretta wrote:
>>> However, because metadata should not be stored in the comment field,
>> 
>> Unfortunately the ship has already sailed on that one when it comes to FITS, due to the use of comments to store unit information.
>> 
> I had fought that one, on the argument that there is no good reason to use anything but the base SI units (e.g. meters, not kilometers), but I was outvoted ;-) As you say, that ship has sailed...

The ship has sailed, but like all ships can return to port whenever we like.

As with the other issues of long keyword names and values, versioning, inheritance, etc, we can address units when transitioning from the current ASCII headers to a binary table metadata representation.  Just add a column for units.  A column for an (optional) timestamp.  And a separate column for human-readable comments with no special-handling for units or timestamps.

Rob