[MathML-Last-Call] Inherited attributes and default values

The mstyle element (section 3.3.4.1) specifies that an attribute that
is not normally inherited, such as linethickness on mfrac, may have a
default value that may be changed by an attribute on mstyle.

Some clarification is needed for cases of inherited attributes that are
given default values on other elements.  The troublesome attributes are
displaystyle and scriptsizemultiplier.

If the default value should override the inherited value, then mstyle
cannot be used to change the default value, as it is described to do
for other attributes.  If the inherited value should override the
default value, then the default value for these attributes has no
meaningful effect.

Suggested changes:

1) displaystyle on mtable (section 3.5.1)

displaystyle on mtable should be marked as an inherited attribute,
and the text should describe that mtable makes an automatic change
to set displaystyle to false if the attribute is not present.

This is how displaystyle is described for other elements that make
automatic changes to displaystyle and/or scriptlevel.

As on other elements, the automatic change should override the
inherited value.

2) displaystyle on mscarries (section 3.6.5)

The mscarries element should make an automatic change to set
displaystyle to false, to match other elements that change the
scriptlevel.

As on other elements, the automatic change should override the
inherited value.

3) scriptsizemultiplier on mscarries (section 3.6.5)

scriptsizemultiplier on mscarries should be marked as an inherited attribute,
and the text should describe that mscarries makes an automatic change to the
default value that is used in its child elements.  The description should
specify that while mscarries changes the default value, it uses the inherited
value if one has been set.

This way, mstyle can be used to supply the inherited value for mscarries,
and mscarries can use the specialized default value if the inherited value
has not been set by mstyle.

Received on Monday, 9 November 2009 18:59:39 UTC