[XeTeX] xunicode and \textlbrackdbl

[Ross Moore]

Hi Alan,

On 15/11/2010, at 5:57 AM, Alan Munn wrote:

> Hi,
> 
> In xunicode.sty there's some preliminary definitions for \textrbrackdbl and \textlbrackdbl  that appear after the \endinput (and are therefore not standardly defined.) The suggested definition use x301A and x301B (which come from CJK Symbols and Punctuation)  as the UTF character.  

I wouldn't use these, unless you want them in CJK blocks.

> Is there a reason for using this as opposed to x27E6 and x27E7 (which come from Miscellaneous Math Symbols-A)?  More fonts seem to have the latter code points.

Sure. The comment in Xunicode is:

>>> % Not many fonts support these code-points yet.
>>> % So leave these undefined at present.
>>> 
>>> \DeclareUTFcharacter[\UTFencname]{x3008}{\textlangle}
>>> \DeclareUTFcharacter[\UTFencname]{x3009}{\textrangle}
>>> \DeclareUTFcharacter[\UTFencname]{x301A}{\textlbrackdbl}
>>> \DeclareUTFcharacter[\UTFencname]{x301B}{\textrbrackdbl}


For the single angle brackets the names are  \textlangle and \textrangle
whereas the math symbols have been  \langle  and  \rangle  since the 
beginning of TeX.

With the double angle brackets, these were often done in (La)TeX math
as  \lbrack\!\lbrack  etc.
But now that there is a Unicode slot for these, the math symbol should
have a macro name in  unicodemath.sty 's list of symbols.

I'm not sure whether I just made up  \textlbrackdbl and \textrbrackdbl
or whether they exist already in (an)other package(s).

In any case, they occur after \endinput  so do not affect your
coding at all. They are put there as preparatory to further work,
which may in fact never take place. 
Being CJK characters, there needs to be input from others more familiar 
with how these characters are meant to be used.

> 
> (This is sort of a moot point at the moment, but I use these characters quite a bit so I just copied the definitions from xunicode until I discovered that in the fonts I was using they're in Misc. Math-A.)

Sure, as math symbols. So if you are doing math, then those are the
ones you should be using, and Xunicode is not involved at all.

However, if you are putting them in text, having some exotic meaning 
which is different from what they mean in CJK, then I have no opinion
about which code-points you should be using.

Indeed, in such a case I would advise that you make up your own 
macro name for use in the document body. Then in your preamble
define how you get the glyph, and include comments about 
this choice and whether it may not be best for future usage.


> 
> Alan
> 
> -- 
> Alan Munn
> amunn at gmx.com


Hope this helps,

	Ross


------------------------------------------------------------------------
Ross Moore                                       ross.moore at mq.edu.au 
Mathematics Department                           office: E7A-419      
Macquarie University                             tel: +61 (0)2 9850 8955
Sydney, Australia  2109                          fax: +61 (0)2 9850 8114
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