Re: [Imgcif-l] CBF - Adding binary proprietary format header dump

[Brian McMahon <bm@iucr.org>]

Not my place to get into the discussion as to whether or not
Justin's proposal is desirable, but just to draw attention to
a couple of technical points about it:

> We here would, in fact, like to add our binary header to the CBF file. 
> Should that just go into an additional binary section, with MIME header 
> and all of that?  If so, is there any recommendation as to how we can 
> refer to it in the CIF headers so that I can distinguish between the 
> binary image data and our binary header data?  My inclination is to add 
> the ".header_convention" column to my "_array_data" loop and fill it in 

Is _array_data.header_convention an agreed term in the current draft
dictionary? If not, one should either request (via the imgcif-l list)
that it be added, following due community discussion, or register a
namespace prefix for your local use at
    http://www.iucr.org/cgi-bin/cifreserve.pl?add

If you registered "rayonix", say, you would then be at liberty to insert
   _array_data.rayonix_header_convention

> with "RAY_1.0" or something like that for the our binary header and with 
>   an empty value "" for the image data.

Since CIF is free-format, you can't have an unquoted blank as a null field.
Instead use a single period character:
 
loop_
_array_data.array_id
_array_data.binary_id
_array_data.header_convention
_array_data.data
  ARRAY1 1 RAY_1.0
;
--CIF-BINARY-FORMAT-SECTION--
<<MIME header for Rayonix binary header dump>>
<<Rayonix binary header dump>>
--CIF-BINARY-FORMAT-SECTION----
;
  ARRAY2 2  .                     #<<<<<<< Note the placeholder period
;
--CIF-BINARY-FORMAT-SECTION--
<<MIME header for image binary data>>
<<Image binary data>>
--CIF-BINARY-FORMAT-SECTION----
;


Cheers
Brian
_________________________________________________________________________
Brian McMahon                                       tel: +44 1244 342878
Research and Development Officer                    fax: +44 1244 314888
International Union of Crystallography            e-mail:  bm@iucr.org
5 Abbey Square, Chester CH1 2HU, England
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