On 2005/11/28 02:10:19 +0 Vin Shelton committed in "stable" `release-21-4' branch this change. 2005-04-05 Aidan Kehoe <kehoea(a)parhasard.net&gt; * mule-ccl.c (ccl_driver): Calculate the charset and position code for control-1 characters properly, both when reading multibyte characters and writing them. This changes what `write-multibyte-character' CCL instruction writes when passed a representation of `control-1' charset character. So the change is obviously visible to lisp programmer. Still it is not noted in `NEWS' file. `control-1' emchars are just like any others, and coding systems decoding data to these emchars certainly make sense. How do we implement such a coding systems in CCL? Assume that CCL program have prepared generic emchar representation for `write-multibyte-character' in its registers, and this emchar may be or not be in `control-1' charset. How do we have it write `control-1' emchar out after that change? Another issue is that emchar value being written out for `(control-1 CODE)' chars, 0 <= CODE < 32, is negative, which makes little sense.

Please resolve the issue. Perhaps you decide to revert the change. Or perhaps you devise and recommend the workaround. Then please note the change in <Lisp and internal changes> section of `NEWS' with stating how to work around that, how to write `control-1' emchars out.