2 files changed, 24 insertions, 3 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 9a0f0f83e27..3df349fd7e9 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2567,9 +2567,16 @@ the Macintosh but may be used generally for Macintosh-encoded text.
 introduced for Unicode characters in the range U+0100..U+24FF,
 U+2500..U+33FF, U+E000..U+FFFF respectively.
 
-** The new coding system `mule-utf-8' has been added.  It provides
-limited support for decoding/encoding UTF-8 text.  For details, please
-see the documentation string of this coding system.
+Note that the character sets are not yet unified in Emacs, so
+characters which belong to charsets such as Latin-2, Greek, Hebrew,
+etc. and the same characters in the `mule-unicode-*' charsets are
+different characters, as far as Emacs is concerned.  For example, text
+which includes Unicode characters from the Latin-2 locale cannot be
+encoded by Emacs with ISO 8859-2 coding system.
+
+** The new coding system `mule-utf-8' has been added.
+It provides limited support for decoding/encoding UTF-8 text.  For
+details, please see the documentation string of this coding system.
 
 ** The new character sets `japanese-jisx0213-1' and
 `japanese-jisx0213-2' have been introduced for the new Japanese
diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index 5ae962a2eea..a3bf833e4d0 100644
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -668,6 +668,20 @@ from Emacs 19.34 distribution:
   Specifying a different independent variable name will affect the
   resulting formula: @kbd{a F 1 k RET} produces @kbd{3 + 2 k}.
 
+* Unicode characters are not unified with other Mule charsets.
+
+As of v21.1, Emacs charsets are still not unified.  This means that
+characters which belong to charsets such as Latin-2, Greek, Hebrew,
+etc. and the same characters in the `mule-unicode-*' charsets are
+different characters, as far as Emacs is concerned.  For example, text
+which includes Unicode characters from the Latin-2 locale cannot be
+encoded by Emacs with ISO 8859-2 coding system; and if you yank Greek
+text from a buffer whose buffer-file-coding-system is greek-iso-8bit
+into a mule-unicode-0100-24ff buffer, Emacs won't be able to save that
+buffer neither as ISO 8859-7 nor as UTF-8.
+
+To work around this, install some add-on package such as Mule-UCS.
+
 * The `oc-unicode' package doesn't work with Emacs 21.
 
 This package tries to define more private charsets than there are free