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From: Michael Enright <mike@kmcardiff.com>
Date: Tue, 26 Jun 2018 14:39:35 -0700
Message-ID: <CAOC2fq-OZE1DvG_p1tcVpfJHD3x2rg2nmiY1ox8mAoVSEM3S7w@mail.gmail.com>
Subject: Re: UTF-8 character encoding
To: cygwin@cygwin.com
Content-Type: text/plain; charset="UTF-8"

On Mon, Jun 25, 2018 at 11:33 AM, Lee <ler762@gmail.com> wrote:
> I'm still trying to figure utf-8 out, but it seems to me that 0x0 -
> 0xff is part of the utf-8 encoding.

I don't see how you arrived at this. An initial byte of 0xFF is not
the initial byte of any valid UTF-8 byte sequence. And it doesn't
conform with the statement you have later:

>  An easy way to remember this transformation format is to note that the
>  number of high-order 1's in the first byte is the same as the number of
>  subsequent bytes in the multibyte character:

This is true, but there is also a zero bit that ends the
high-order-1's bit string, which means that 0xFF is not a valid lead
byte. 0x7F is the highest byte value that you can have as a
single-byte UTF8 string.

Perhaps your statement about 0-0xFF was meant to be read differently.

Thomas Wolff's note seems to be objecting to the inclusion of
characters above U+10FFFF which isn't legal UTF-8, but was in the
original proposal. Otherwise your table rows 1-4 is correct.

The standards such as IETF RFC-3629 are easy enough to read, so I
recommend using them and citing them to others instead of trying to
summarize.

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