It’s a bit odd: if you assume the default is ascii then you don’t need this. If you assume the default is utf8 then you don’t need this... so when do you need the BOM? It seems like making bad prior choices more acceptable... even though they were bad choices. I’m not sure it’s a good idea. 

On Sun, Oct 11, 2020 at 8:22 PM Tom Honermann via SG16 <sg16@lists.isocpp.org> wrote:
On 10/10/20 7:58 PM, Alisdair Meredith via SG16 wrote:
One concern I have, that might lead into rationale for the current discouragement,
is that I would hate to see a best practice that pushes a BOM into ASCII files.
One of the nice properties of UTF-8 is that a valid ASCII file (still very common) is
also a valid UTF-8 file.  Changing best practice would encourage updating those
files to be no longer ASCII.

Thanks, Alisdair.  I think that concern is implicitly addressed by the suggested resolutions, but perhaps that can be made more clear.  One possibility would be to modify the "protocol designer" guidelines to address the case where a protocol's default encoding is ASCII based and to specify that a BOM is only required for UTF-8 text that contains non-ASCII characters.  Would that be helpful?


Tom.


AlisdairM

On Oct 10, 2020, at 14:54, Tom Honermann via SG16 <sg16@lists.isocpp.org> wrote:

Attached is a draft proposal for the Unicode standard that intends to clarify the current recommendation regarding use of a BOM in UTF-8 text.  This is follow up to discussion on the Unicode mailing list back in June.

Feedback is welcome.  I plan to submit this to the UTC in a week or so pending review feedback.

Tom.

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