Re: DRAFT: eXIF 2017-03-05

On 5 March 2017 at 09:47, Glenn Randers-Pehrson <[email protected]> wrote:
> DRAFT
> eXIf 2017-03-05
> http://www.simplesystems.org/png-group/proposals/eXIf/
> png-proposed-eXIf-chunk-03-05.html
> Glenn Randers-Pehrson <[email protected]>

Hi,

The latest eXIf draft looks good. May I please suggest one small
editorial (i.e. non-semantic) change: don't just check the endianness
bytes; check the entire TIFF/EXIF "philosophical" signature instead.

Instead of:

"Decoders should check the first two bytes of data to ensure that they
are "II" or "MM"."

We can be more specific and say:

"Decoders should check the first four bytes of data to ensure that
they are "II\x2a\x00" or "MM\x00\x2a"."

Or even be encoding-agnostic and say:

"Decoders should check the first four bytes of data to ensure that
they are "\x49\x49\x2a\x00" or "\x4d\x4d\x00\x2a"."

Or use base 10 (as it is customary in the rest of the PNG
specification) and say:

"Decoders should check the first four bytes of data to ensure that
they have the following decimal values:
<pre>
    73, 73, 42, 0
</pre>
or
<pre>
    77, 77, 0, 42
</pre>"

Sincerely,
Cosmin

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