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Re: lmoustache/rmoustache as stretchy delimiters

From: Neil Soiffer <NeilS@dessci.com>
Date: Sat, 29 Aug 2015 23:45:14 -0700
Message-ID: <CAESRWkBFSOnSUo7P2gBvjaa-H6-jozidDpne7HHWXC6m1FqCuQ@mail.gmail.com>
To: Frédéric Wang <fred.wang@free.fr>
Cc: "www-math@w3.org" <www-math@w3.org>
I'm kind of dubious about including U+23B0 and U+23B1. Unicode says these
are:
U+23B0 <http://www.fileformat.info/info/unicode/char/23b0/index.htm> UPPER
LEFT OR LOWER RIGHT CURLY BRACKET SECTION ⎰ [image: sample of UPPER LEFT OR
LOWER RIGHT CURLY BRACKET SECTION (U+23B0)]
U+23B1 <http://www.fileformat.info/info/unicode/char/23b1/index.htm> UPPER
RIGHT OR LOWER LEFT CURLY BRACKET SECTION ⎱ [image: sample of UPPER RIGHT
OR LOWER LEFT CURLY BRACKET SECTION (U+23B1)]



Are you sure you have the mapping of lmoustache/rmoustache correct? It
seems very strange to map them to a piece of a *vertical *delimiter. Of
course, there's nothing stopping you from adding them to Gecko's operator
dictionary, but if we added these to the one in the spec, why not add all
the other pieces?

In general, I suppose it's not an unreasonable assumption to assume that if
a piece of a stretchy operator is used as an operator, then it has the
properties of the entire delimiter. On the other hand, if someone is using
a piece of a stretchy char, I suspect they are making up their own operator
and who knows what its default properties should be.

As with David's reply, just my own opinion and not necessarily that of the
Math WG.

Neil Soiffer
Senior Scientist
Design Science, Inc.
www.dessci.com
~ Makers of MathType, MathFlow, MathPlayer, MathDaisy, Equation Editor ~



On Fri, Aug 28, 2015 at 8:05 AM, Frédéric Wang <fred.wang@free.fr> wrote:

> Dear all,
>
> It seems that lmoustache/rmoustache have been used as MathML stretchy
> operators for a long time. For example, itex2MML provides the \lmoustache &
> \rmoustache commands to generate these delimiters:
>
>
> https://golem.ph.utexas.edu/~distler/blog/itex2MMLcommands.html#itex2MMLDelim
>
> and Gecko has entries for U+23B0 and U+23B1:
>
>
> https://dxr.mozilla.org/mozilla-central/source/layout/mathml/mathfont.properties?offset=300#1137
>
> However, the MathML Operator dictionary does not contain any mention of
> lmoustache/rmoustache:
>
> http://www.w3.org/TR/MathML3/appendixc.html
>
> Should they be added to the official MathML dictionary or are they
> excluded on purpose?
>
> Frédéric
>
>
Received on Sunday, 30 August 2015 06:45:43 UTC

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