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Re: [MathML3-last-call] Clarify how "symmetric" should be set by the Operator Dictionary

From: Neil Soiffer <neil.soiffer@gmail.com>
Date: Tue, 29 Sep 2009 16:32:19 -0700
Message-ID: <d98bce170909291632m5efd0f3fp85d5034cd46d66ab@mail.gmail.com>
To: Frédéric WANG <fred.wang@free.fr>
Cc: "www-math@w3.org" <www-math@w3.org>
Thanks for spotting that.  Upon discussing this, some WG members felt that
the default should be symmetric='true' for when someone says to stretch
something.  That's true for fences, but for arrows, the main use case is in
a mtable and there they should not stretch symmetrically.

The tentative conclusion was that  we should remove the sentence in 3.2.5
and do a better job of finding fences in Unicode and defaulting them to
symmetric in Appendix C (even though very few fonts will be able to stretch
many of them).  That gets the right behavior and allows us to continue to
have a compact form for the table in Appendix C.

While modifying Appendix C, we will try to list more of the arrows as being
stretchy (even though most fonts don't support stretching them easily).

Does anyone object to this approach?

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

2009/9/28 Frédéric WANG <fred.wang@free.fr>

> I like the compact form to list boolean valued properties of an operator in
> Appendix C. However, in the section that describes the format of operator
> dictionary entries, these rules are given in order to set their values:
> "Boolean valued attributes such as stretchy are specified together in the
> final Properties column by listing the attribute name if its value should be
> set to true by the dictionary."
> and "Any attribute not listed for some entry has its default value, which
> is given in parentheses in the table of attributes in Section 3.2.5
> Operator, Fence, Separator or Accent <mo>."
> If I read this correctly, the "symmetric" property should be set to "true"
> when it is present and to its default value when it is not. But its default
> value is still "true" according to section !
Received on Tuesday, 29 September 2009 23:32:57 UTC

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