v4.6

• new macros \xetexkoprehanjaspacing and \xetexkoposthanjaspacing,
  which users can insert before and after a command (eg., \ruby)
  to produce appropriate inter-character spacing around the command

v4.5

• new command \xetexkostretchshrink.
  • The argument shall be stretch and shrink part of a glue, for instance plus .025em minus .015em, which will be used for inter-character glue between CJK characters.

v4.4

• change char class of some traditional chinese chars
• use LaTeX's build/page/before hook if available

v4.3

use e-type instead of x-type in EXPL code

v4.2

use kernel's selectfont

v4.1

• assign U+223C (tilde operator) to \XeTeXcharclassSY (cjksymbols)
• avoid possible clash with unicode-math package

v4.0

• generalize the concept introduced at v3.9, that is \ifx\f@encoding\UTFencname now affects inter-character spacing as well as font substitution.
• guard against space character(catcode 12) in parsing code point of next character

v3.9

• substitution with hangul/hanja fonts will now occur only when \ifx\f@encoding\UTFencname is true. On plain TeX this is normally true as both are undefined.
• pronuntiation of U+4F53 is now CHEY.
• do not delay loading of konames-utf.sty

v3.8

• assign 0xAE and 0xB0 to XeTeXcharclassAA

v3.7

• fix position of dotemph regarding hangul tone marks
• enhance compatibility with ulem/ruby packages