[fitsbits] Endian state of multibyte Binary Data in FITS files

[Milton Aupperle]

In article <3EA93251.1030204 at nasa.gov>, Tom McGlynn
<Thomas.A.McGlynn at nasa.gov> wrote:

> Milton Aupperle wrote:
> ...
> > Can anyone suggest a URL where I can find out about how to indicate or
> > determine what Endian multibyte data is in?
> ...
> 
> All FITS data are big-endian.  This is described at the beginning
> of section 6 in the FITS standard:
> 
>    Primary and extension data shall be represented in one of the formats
> described in this
>    section. FITS data shall be interpreted to be a byte stream. Bytes are in
> order of
>    decreasing signicance. The byte that includes the sign bit shall be first,
> and the byte
>    that has the ones bit shall be last.
> 
>  Regards,
>  Tom McGlynn
> 
> 
> [P.S., Aside for the FITS lawyers:
> I'm not sure the last phrase is written very well.
> It's not clear to me what the 'ones' bit
> is for floating point data.  It could be interpreted as
> the bit that is multiplying 2^0 and that can occur in any
> of the bytes of an IEEE number or none.  I'm not sure
> what else it would mean for real numbers.  The phrasing apparently
> just has integers in mind.]

Thanks everyone for the help both on and offline.

When i was looking for this info in the Fits specifiactions, I searched
for the word "endian" - thinking that the definition/descrition would
be more like

"Multi byte binary data shall be in the xxxx endian format"

but as I can see from Tom's info above, I missed it.

Once again thanks..

Milton Aupperle
milton (at) outcastsoft (dot) com
www.outcastsoft.com