Re: Display of undisplayable characters: \U01F3A8 instead of diamond

[Yuri Khan]

On Fri, 26 Aug 2022 at 15:24, Emanuel Berg <incal@dataswamp.org> wrote:


> As for what char it was, it looked like these two - and they
> look the same in a Linux VT -
>
> \u2666 ♦        BLACK DIAMOND SUIT
> \u25c8 ◈        WHITE DIAMOND CONTAINING BLACK SMALL DIAMOND

Linux console works over (an emulation of?) the VGA text mode, which
descends from IBM CGA text mode, whose set of displayable characters
was defined by code page 437. Its codes 0x03 through 0x06 encoded
playing card suits — hearts, diamonds, clubs, spades, in this order.
In Unicode, these became U+2665, U+2666, U+2663, U+2660, respectively.

I do not know the history of replacing an undisplayable character with
a diamond. The U+FFFD Replacement Character glyph looks similar, but
the cause/consequence link might be in either direction.