- From: Bruce Smith <bruce@wolfram.com>
- Date: Thu, 29 Jan 1998 22:30:40 -0800
- To: Andreas Strotmann <strotman@klein.math.fsu.edu>
- Cc: www-math@w3.org, strotmann@rrz.uni-koeln.de, w3c-math-wg@w3.org

[was: Re: some proposals on MathML] To reply just to your "units=" proposal: At 3:35 PM 1/28/98, Andreas Strotmann wrote: ... > - may I propose a "units=" attribute for the <cn> and <ci> elements > or some other mechanism for specifying units (physical, monetary, > or otherwise)? > In high school textbooks you will often find questions that give > numbers in terms of certain units, and not all numbers in the same > units either (e.g. a geometry question may involve the lenght of > the thumb and the distance between eye and thumb in inches, give the > height of an object at a distance in feet, and ask for the distance to > that object in miles). > Possible values of the units attribute may or may not be included in > the MathML definition, but the list should definitely be extensible. > It may be better to do this by introducing a qualifier element <unit> > instead that <cn> and <ci> may take, or by introducing a general > purpose <unit> element whose first argument would represent the > quantity and whose first element would represent the unit expression > (km/sec^2, say, in MathML markup). > This would greatly improve the utility of MathML in the rest of the > sciences, and even more outside the sciences, I would think. I fully agree that support for quantities with units is desirable. But I think we already support this, merely by allowing expressions consisting of products of numbers and identifiers. For example, the quantity 9.8 meter/(second ^ 2) could be expressed directly as the MathML markup corresponding to that expression, 9.8 meter/(second ^ 2), using identifiers such as <ci>meter</ci>. If <ci>meter</ci> is not thought to be sufficiently unambiguous, then I'd suggest using the definition attribute on <ci> to make it unambiguous. (I don't know whether this attribute was present in the Jan 6 version of the draft. It will permit marking certain MathML expressions with a "definition" attribute, whose format is not specified except that it can be a URL; this is enough to allow someone owning a certain domain name to establish a convention that expressions marked with definitions which are URLs in that domain mean what that someone says they mean.) (I concentrate on Chapter 3, so I don't know for sure that <ci> accepts the definition attribute, but I would guess and hope it does.) - Bruce Smith bruce@wolfram.com

Received on Friday, 30 January 1998 01:31:09 UTC