[TUHS] Anyone know what a LANTERN is?

Alan D. Salewski salewski at att.net
Sat Jul 29 17:06:33 AEST 2017

On 2017-07-28 13:46:40, Paul Ruizendaal spake thus:
> > Message: 1
> > Date: Thu, 27 Jul 2017 11:58:38 -0400
> > From: Random832 <random832 at fastmail.com>
> > To: tuhs at minnie.tuhs.org
> > Subject: [TUHS] Anyone know what a LANTERN is?
> > Message-ID:
> > 	<1501171118.69633.1054588920.11864815 at webmail.messagingengine.com>
> > Content-Type: text/plain; charset="utf-8"
> > 
> > There is a character in the terminfo/curses alternate character set,
> > ACS_LANTERN, which is mapped to "i" in the VT100 alternate grapical
> > character set. This character is, in fact, on a real VT100/VT220 (and
> > therefore in most modern terminal emulators that support the full ACS),
> > "VT" (in 'control character picture' format, along with HT FF CR LF NL).
> > The ASCII mapping uses "#", and some CP437/etc mappings map it to the
> > double box drawing intersection character.
> > 
> > Was there ever a real 'lantern' character? The manpage mentions "some
> > characters from the AT&T 4410v1 added". What did it look like?
> There's two references in the termcap manpages:
> http://invisible-island.net/ncurses/man/terminfo.5.html
> and
> http://invisible-island.net/ncurses/man/curs_add_wch.3x.html
> The second link mentions that the AT&T 4410 terminal added this glyph in the location of the VT100 VT glyph. Apparently what it looked like is lost, unless someone finds a detailed 4410 manual (or has a working one in the attic).

The wecho_wchar(3ncurses) page[0] on my Debian box happens to mention
the following[1] in a discussion about incorporating Unicode support:

    ·   The lantern is a special case.  It originated with  the  AT&T  4410
        terminal  in the early 1980s.  There is no accessible documentation
        depicting the lantern symbol on the AT&T terminal.

        Lacking documentation, most readers assume that a storm lantern was
        intended.  But there are several possibilities, all with problems.

        Unicode  6.0  (2010)  does provide two lantern symbols: U+1F383 and
        U+1F3EE.  Those were not available  in  2002,  and  are  irrelevant
        since  they  lie  outside the BMP and as a result are not generally
        available in terminals.  They are not storm lanterns, in any case.

        Most storm lanterns have a tapering glass chimney (to guard against
        tipping); some have a wire grid protecting the chimney.

        For  the  tapering  appearance, ☃ U+2603 was adequate.  In use on a
        terminal, no one can tell what the image represents.  Unicode calls
        it a snowman.

        Others  have suggested these alternatives: § U+00A7 (section mark),
        Θ U+0398 (theta), Φ U+03A6 (phi), δ U+03B4 (delta), ⌧ U+2327 (x  in
        a  rectangle), ╬ U+256C (forms double vertical and horizontal), and
        ☒ U+2612 (ballot box with x).

[0] From a version 6.0+20170715-2 of the 'ncurses-doc' package:

        $ man -aw wecho_wchar

        $ dpkg -S $(man -aw wecho_wchar)
        ncurses-doc: /usr/share/man/man3/add_wch.3ncurses.gz

        $ dpkg -l ncurses-doc | grep '^i'
        ii  ncurses-doc    6.0+20170715-2    all    developer's guide and documentation for ncurses

[1] Which, AFAICT is a recent addition to the page, documented by the
    below NEWS file entry:

    <quote src="http://invisible-island.net/ncurses/NEWS.html#index-t20170506">
                + improve discussion of line-drawing characters in curs_add_wch.3x
                  (prompted by discussion with Lorinczy Zsigmond).

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