[fitsbits] FITS Errata. {External}

[William Pence]

Regarding known errors in the FITS Standard document, I think an Errata page should be placed online until such time as a new version of the document can be produced. Here are 3 items I know of:

1.  Section 10.1.3:  This sentence “If the heap is larger than 2.1 GB, then the ‘1Q’ format (which uses 64-bit pointers) must be used.” is incorrect because the ‘1P’ format can also produce a heap that is larger than 2.1 GB. See my email to fitsbits on 26 Oct 2023 for a suggested rewording of this section. 

2.  Section 10.2.1:  In the sentence "... pixels in the floating-point image that are exactly equal to 0.0 are represented by the reserved value -2147483647 in the quantized integer array...", the reserved value should be -2147483646.

3.  Section 10.3.6:  In the recipe for compressing variable-length array columns, the sentence that says append one set of variable-length array descriptors after another set is backwards. The 2 sets should be combined in the opposite order. 


Does anyone know of any other errors or any sections in the Standard that need clarification?

Bill

> On Mar 28, 2024, at 1:05 PM, Pierre Fernique via fitsbits <fitsbits at listmgr.nrao.edu> wrote:
> 
> 
> 
> 
> Hi all,
> 
> Le 28/03/2024 à 00:43, Seaman, Robert Lewis - (rseaman) via fitsbits a écrit :
>> Does Rubin have any other suggestions for updating the standard? By all means make a list. The standard is not frozen, even if the procedures may be a bit quaint.
>>  
>> Rob
> As the standard is not frozen 😉, I'd like to take this opportunity to recall the following discrepancies raised one year ago between the current description of the RICE decompression method in the standard (4.0), and the actual implementation in the latest version of CFITSIO (see below for details).
> 
> More generally, regarding the easiness / difficulty of implementing the new document's recommendations, it would be interesting to know which alternative libraries to CFITSIO have already partially or fully implemented the document compression/decompression recommendations. A new column in the table described here https://fits.gsfc.nasa.gov/fits_libraries.html would be very valuable for evaluating this question.
> 
> Best regards,
> Pierre Fernique
> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listmgr.nrao.edu/pipermail/fitsbits/attachments/20240328/64381c5a/attachment.html>