Re: [dispatch] [media-types] 3rd WGLC - draft-ietf-dispatch-javascript-mjs - deadline 10th May

["Martin J. Dürst" <[e-mail]>]

On 2021-05-18 20:39, Mathias Bynens wrote:
> Comment inline
> 
> On Tue, May 18, 2021 at 12:18 PM Graham Klyne <[e-mail]>
> wrote:

>> 2. I couldn't understand the section on character encoding detection (sect
>> 4.2),
>> in particular this paragraph:
>>
>> [[
>>          Implementations of this step MUST use these octet sequences to
>>          determine the character encoding scheme, even if the determined
>>          scheme is not supported.  If this step determines the character
>>          encoding scheme, the octet sequence representing the Unicode
>>          encoding form signature MUST be ignored when decoding the binary
>>          source text.
>> ]]
>>
>> I'm probably misunderstanding something here, but it seemed
>> self-contradictory
>> to me (if the unicode encoding signature is used to determine the
>> encoding, it
>> must be ignored...?)
>>
> 
> Happy to clarify. This is about the Unicode Byte Order Mark (BOM), which
> should be stripped from the file's contents before processing it. More info
> here: https://en.wikipedia.org/wiki/Byte_order_mark (This is not specific
> to this draft, or even to ECMAScript — it’s a general Unicode concept.)
> 
> Note that this language is not new to this draft; it's inherited
> from RFC4329 which this document supersedes.

It is indeed somewhat difficult to understand for people who are not 
familiar with the BOM, and autodetection proceedures.

I'd suggest changing:

If this step determines the character
encoding scheme, the octet sequence representing the Unicode
encoding form signature MUST be ignored when decoding the binary
source text.

to something such as:

If this step determines the character
encoding scheme, the octet sequence representing the Unicode
encoding form signature is not part of the actually decoded binary
source text.

Regards,   Martin.