I could just say:

  I agree, as ever:-), with David

But that would imply that I have read all this!!

As a user of multi-letter math symbols on strange fonts, such as 'upper case sans serif Demi-bold' I am happy with the Classic TeX/LaTeX methods for getting what I want and feel that the LaTeX version \mathsfdbf ?? captures well the visual or presentation semantics.  Also, as a mathematician I do not think that the Plane 1 math letters have any semantics other than this type of 'visual  meaning'. [ For physicists they will have physical semantics, but inconsistently and with multiplicities of meaning in different application areas.]  The Unicode philosophy and logic are purely the invention of a group of computing and standards people who pretend to understanding how math and science people use math language and written notation; thus they have no relevance to me as a math person BUT there work is both painstaking and excellent as informatics and of great use to my other hats.

And I will look at it all in more detail RSN.

Chris 



Sent from my iPud (\~/)

> On 20 May 2014, at 20:19, Barbara Beeton <[log in to unmask]> wrote:
> 
> On Tue, 20 May 2014, Joseph Wright wrote:
> 
>    [...]
> 
>> In contrast, Unicode math defines a number of alphabets in a single Unicode
>> font, including mathematical italic and bold mathematical italic and many
>> more variations. In OpenType maths fonts to date, these symbols are all
>> designed as single-letter identifiers and not to be used for strings of
>> characters such as "Re" in italic or "Set" in bold.
> 
>    To be clear, the Unicode position is that e.g. bold-B for magnetic field
>    should not come from the 'bold' font but from the bold-symbols part of a
>    single maths font: correct? That being the case, have the Unicode people
>    considered at all multi-letter identifiers or has this simply been
>    missed at present? (Anyone on the list sufficiently well-informed about
>    this?)
> 
> having been the stix representative to
> the unicode technical committe, i hope
> that i'm sufficiently well-informed.
> 
> the unicode people didn't consider
> multi-letter identifiers specifically,
> since only single letters are (normally)
> given character status.  as pointed out
> (i think by david), one goal of the
> alphanumeric block in plane 1 was to
> be able to drop single characters into
> text and have them recognized as math
> identifiers (one of the "math subgroup"
> was murray sargent of microsoft, who
> has been responsible for the ms work
> adding math to office).  another
> explicit goal was to be able to search
> for individual math expressions by
> unicode to find in what documents a
> particular identifier had been used.
> explicitly *un*intended was the
> ability to easily use, say, fraktur
> or script for wedding invitations,
> hence the location in plane 1.
> 
> the unicode goal is to have only one
> code per "meaning".  hence the absence
> of the "usual version" of an alphabet
> (usually upright lightface) from the
> plane 1 math block.  (the absence of
> lightface sans greek is an oversight;
> this has been resubmitted, with a
> reference to nist special publication 811,
>  http://physics.nist.gov/cuu/pdf/sp811.pdf
> page 22, where lightface sans is used,
> though not by name, in the definition
> of the *dimensions* of si base quantities.
> one greek letter, theta, is shown; not
> sure whether the theta is upper- or
> lowercase, but it's the principle
> that's important to the utc.)  more
> information (and history regarding the
> deciding example that resulted in the
> inclusion of the plane 1 alphanumeric
> block) is given in unicode tech report #25:
>  http://www.unicode.org/reports/tr25/
> 
> regarding identifiers, see utr#25, in
> particular sections 2.16 and 4.4.  (the
> latter section does strongly hint that
> the characters in the plane 1 block can
> be used for multi-letter identifiers.)
> 
> hope this is helpful.
>                        -- bb