Feedback on the proposal to change U+FFFD generation when decoding ill-formed UTF-8

Karl Williamson via Unicode unicode at
Mon May 15 22:23:06 CDT 2017

On 05/15/2017 04:21 AM, Henri Sivonen via Unicode wrote:
> In reference to:
> I think Unicode should not adopt the proposed change.
> The proposal is to make ICU's spec violation conforming. I think there
> is both a technical and a political reason why the proposal is a bad
> idea.

Henri's claim that "The proposal is to make ICU's spec violation 
conforming" is a false statement, and hence all further commentary based 
on this false premise is irrelevant.

I believe that ICU is actually currently conforming to TUS.

The proposal reads:

"For UTF-8, recommend evaluating maximal subsequences based on the 
original structural definition of UTF-8..."

There is nothing in here that is requiring any implementation to be 
changed.  The word "recommend" does not mean the same as "require". 
Have you guys been so caught up in the current international political 
situation that you have lost the ability to read straight?

TUS has certain requirements for UTF-8 handling, and it has certain 
other "Best Practices" as detailed in 3.9.  The proposal involves 
changing those recommendations.  It does not involve changing any 

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