[XeTeX] pointing angle brackets

[Sven Siegmund]

> > Tho' it may be off-topic, if anyone can say what the difference (in
> > design or functionality) is supposed to be between the angle brackets at
> > U+2329 U+2330 and the mathematical angle brackets at U+3008 and U+3009,
> > it would be very useful.
> >
>
>  I'd love to see a document that actually discusses the (intended) use of
> all of the unicode glyphs, ...

Yes, to be precise, there is more of this sort angle bracket-like
characters (I'll take only the left one):

U+003C LESS-THAN SIGN
U+2039 SINGLE LEFT-POINTING ANGLE QUOTATION MARK
U+2329 LEFT-POINTING ANGLE BRACKET
U+27E8 MATHEMATICAL LEFT ANGLE BRACKET
(so far listed in U3000.pdf)
U+276C MEDIUM LEFT-POINTING ANGLE BRACKET ORNAMENT
U+276E HEAVY LEFT-POINTING ANGLE QUOTATION MARK ORNAMENT
U+2770 HEAVY LEFT-POINTING ANGLE BRACKET ORNAMENT

Something of it is discussed in Unicode Book
(http://www.unicode.org/versions/Unicode5.0.0/ch15.pdf, p. 505):

-----
Miscellaneous Mathematical Symbols-A: U+27C0–U+27EF

The Miscellaneous Mathematical Symbols-A block contains symbols that
are used mostly as operators or delimiters in mathematical notation.
Mathematical Brackets. The mathematical white square brackets, angle
brackets, and double angle brackets encoded at U+27E6..U+27EB are
intended for ordinary mathematical use of these particular bracket
types. They are unambiguously narrow, for use in mathematical and
scientific notation, and should be distinguished from the
corresponding wide forms of white square brackets, angle brackets, and
double angle brackets used in CJK typography. (See the discussion of
the CJK Symbols and Punctuation block in Section 6.2, General
Punctuation.) Note especially that the "bra" and "ket" angle brackets
(U+2329 left-pointing angle bracket and U+232A right-pointing angle
bracket, respectively) are now deprecated for use with mathematics
because of their canonical equivalence to CJK angle brackets, which is
likely to result in unintended spacing problems if used in
mathematical formulae.
-------

They get again mentioned on p. 509:

------
Angle Brackets.

U+2329 left-pointing angle bracket and U+232A right-pointing angle
bracket have long been canonically equivalent to the CJK punctuation
characters U+3008 left angle bracket and U+3009 right angle bracket,
respectively. This canonical equivalence implies that the use of the
latter (CJK) code points is preferred and that U+2329 and U+232A are
also "wide" characters. (See Unicode Standard Annex #11, "East Asian
Width," for the definition of the East Asian wide property.) For this
reason, the use of U+2329 and U+232A is deprecated for mathematics and
for technical publication, where the wide property of the characters
has the potential to interfere with the proper formatting of
mathematical formulae. The angle brackets specifically provided for
mathematics, U+27E8 mathematical left angle bracket and U+27E9
mathematical right angle bracket, should be used instead. See Section
15.4, Mathematical Symbols.
------