[whatwg] [HTML5] Editorial: 3.10.18. The |sup| and |sub| elements

David Walbert dwalbert at learnnc.org
Mon Nov 6 06:19:57 PST 2006

On Nov 4, 2006, at 8:00 AM, Matthew Paul Thomas wrote:

>> ...<var>E</var> = <var>m</var> · c<sup>2</sup>
> Is that equation ever legitimately rendered (in physics textbooks  
> etc) with the "m" in a different style from the "c"? If not,  
> perhaps the definition of <var> needs to be expanded to include  
> physical constants.

No, constants and variables are presented identically in equations.  
The student simply is expected to know whether they are constants or  
not. This requires some context, but the equation makes sense only  
with context anyway. If I understand the draft standards correctly  
the var would be defined by a prior dfn element, and that is where  
one would note (if one believed it necessary) that the speed of light  
was constant.

If that equation is considered only algebraically, then E, m, and c  
are treated identically anyway -- there is no difference in how you  
handle them mathematically.

Is var really not meant to include constants represented  
algebraically? That would take semantic markup to a level that seems  
to me frankly silly.

David Walbert
dwalbert at learnnc.org

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