Re: Questions on accent attribute


This is confusing -- not the best designed part of the language perhaps...

The reason it works this way is so that in most cases, one will get
the right accent behavior automatically, without setting any attribute
values explicitly.  The point was to make accent behavior something
that was determined by a lookup in the operator dictionary.

The way I think of it is that is is the attribute on the <mover> that
actually controls the size and position of the overscript, while the
attribute on the <mo> is essentially a semantic hint (just like the
'fence' attribute) that doesn't really affect rendering except

The 'accent' attribute on the <mo> in the script position can't override
an explicitly set value for the 'accent' attribute on the <mover>.  It
just supplies the default value in the case where there is no explicit
value for 'accent' set on the <mover>.

When there is an explicit 'accent' attribute set on the <mover>, then
it doesn't matter how the value is set on the <mo>.  The <mover> won't
look at it, and it doesn't itself change anything about the rendering
of the <mo>.

I'm not sure my explanation will really make anything any clearer, but
I tried!


Dr. Robert Miner                      
W3C Math Interest Group Co-Chair                      651-223-2883
Design Science, Inc.   "How Science Communicates"

------- Original message -------
Date: Sun, 07 Nov 2004 17:51:20 +0900
From: Tokushige Kobayashi <>
Subject: Questions on accent attribute


I am sorry for too many questions, but I can not understand how
the MathML renderer should behave for accent attribute of mover.

There is a description in as follows:
- -------------
The default value of accent is false, unless overscript is an mo element .... 
If overscript is an mo element, the value of its accent attribute is used as the 
default value of accent for mover.
- ------------- 
This sentence says that the value of the child element (mo) influences
the default value of its parent element (mover).

There is also an example as bellow.

  <mover accent="true">
    <mi> x </mi>
    <mo> &Hat; </mo>
  <mover accent="false">
    <mi> x </mi>
    <mo> &Hat; </mo>

As a entry of operator dictionary for &Hat; specifies accent="true", 
the accent of both mo elements will be set as "true". But the rendering
image shows that accent attributes of mo are not effective for
rendering of &Hat.

The description in the spec seems to say that accent attribute
of mover overrides the value of accent attribute of its child (mo).

It seems to be strange that sometimes the attribute of parent
overrides the attribute of its child, but sometimes the attribute
value of child sets the value of its parent.

I hope someone will explain about the spec.

Best regards,

Tokushige Kobayashi
Antenna House, Inc.
WWW (English)
TEL    +81-3-3234-1361(direct call)
FAX    +81-3-3221-9975

Antenna House XSL School
------- End of forwarded message -------

Received on Monday, 8 November 2004 23:46:58 UTC