What extended ASCII character set uses 0x9D?

[Chris Angelico]

On Tue, Aug 22, 2017 at 5:15 PM, Gregory Ewing
<greg.ewing at canterbury.ac.nz> wrote:
> Chris Angelico wrote:
>>
>> a naive ASCII upper-casing wouldn't produce 0x81 either - if it did, it
>> would also convert 0x21 ("!") into 0x01 (SOH, a control character). So
>> this one's still a mystery.
>
>
> It's unlikely that even a naive ascii upper/lower casing algorithm
> would be *that* naive; it would have to check that the character
> appeared to be a letter before changing it.
>
> You might expect bytes >= 0x80 to be classed as non-letters by
> that test, but what if it ignores the top bit or assumes it's
> a parity bit to be left alone? What do you get under those
> assumptions?

Exactly, I do assume that it's checking for it to be a letter. But
everything previously has been on the assumption that it ignores the
top bit. That's how we got this far.

ChrisA