How do U+2571..U+2573 connect?

[Rebecca Bettencourt]

These three box drawing diagonals appear in at least:
- Amstrad CPC
- Mattel Aquarius
- Atari 8-bit
- MSX
- PETSCII
- Kaypro
- Sharp MZ
- Ohio Scientific
- Robotron

See page 11 of:
https://www.unicode.org/L2/L2019/19025-aux-LegacyComputingSources.pdf

See page 5 of:
https://www.unicode.org/L2/L2021/21235-terminals-supplement-sources.pdf

They don't appear in Teletext.

As to how they came to be in Unicode originally, I don't know. Probably
some IBM or DEC character set.

-- Rebecca Bettencourt


On Fri, Mar 31, 2023 at 4:47 PM Kent Karlsson via Unicode <
unicode at corp.unicode.org> wrote:

> I don’t see them in any of the G2 character sets in
>
> https://www.etsi.org/deliver/etsi_en/300700_300799/300706/01.02.01_60/en_300706v010201p.pdf
> (ETSI EN 300 706 V1.2.1 (2003-04) European Standard (Telecommunications
> series) *Enhanced Teletext specification*).
>
> /Kent K
>
> 1 apr. 2023 kl. 01:26 skrev Doug Ewell via Unicode <
> unicode at corp.unicode.org>:
>
> They are in at least the T.101-G2 set, used for teletext.
>
> —Doug
>
>
>
> Sent via the Samsung Galaxy S22 Ultra 5G, an AT&T 5G smartphone
> Get Outlook for Android <https://aka.ms/AAb9ysg>
> ------------------------------
> *From:* Unicode <unicode-bounces at corp.unicode.org> on behalf of Manuel
> Strehl via Unicode <unicode at corp.unicode.org>
> *Sent:* Friday, March 31, 2023 5:23:08 PM
> *To:* unicode at corp.unicode.org <unicode at corp.unicode.org>
> *Subject:* Re: How do U+2571..U+2573 connect?
>
> Thanks for the answer! I almost thought that this was what’s going on.
>  From looking at the Wikipedia page,
> https://en.wikipedia.org/wiki/Box-drawing_character, it seems that those
> three were not part of any larger legacy encoding. (The curved corners
> come from Acorn Computers by the way, acording to that article.)
>
> This leaves me wondering, where those three characters come from at all.
>
> Manuel
>
> Am 01.04.23 um 01:06 schrieb Asmus Freytag via Unicode:
> > The easy answer is that these do not consist of a single set. For
> > example, the single-, double-line regular-stroke symbols and their
> > combinations, form a subset that is supported by the DOS code page
> > 437. Another common DOS code page (850) has only the single-line ones.
> >
> > Neither set contains any element that terminates in the middle of the
> > cell.
> >
> > Those, as well as the heavy stroke or mixed weight combinations are
> > presumably supported somewhere else, as are the curved corners. I
> > don't know off hand what the character sets are from which these were
> > derived, but again, I would not be surprised if they supported only a
> > subset.
> >
> > The diagonals, therefore, are not necessarily from any of those
> > subsets, and therefore likely never intended to be used to provide
> > diagonal connections.
> >
> > A./
> >
> >
> > On 3/31/2023 3:46 PM, Manuel Strehl via Unicode wrote:
> >> Hi,
> >>
> >> if you look at the Box Drawing block, e.g.,
> >> https://codepoints.net/box_drawing, every character goes through the
> >> middle of the edges of an imagined rectangle around the glyph. That
> >> is, apart from U+2571, U+2572 and U+2573, the diagonal lines. Those
> >> touch exclusively the corners of said rectangle.
> >>
> >> I fail to imagine how these three characters could ever attach to any
> >> of the other characters in this block. Are they not meant to do that
> >> or am I missing a trick here?
> >>
> >> Thanks for any pointers!
> >>
> >> Cheers,
> >> Manuel
> >>
> >> PS: This question was triggered by this reddit post:
> >>
> https://www.reddit.com/r/Unicode/comments/127y7dn/looking_for_box_drawing_characters/
> >
> >
>
>
>
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