These charsets return incorrect values for canEncode, only for ASCII:

charset=Big5-HKSCS canEncode=false '\u0000' - '\u007f'
charset=x-Big5-Solaris canEncode=false '\u0000' - '\u007f'
charset=x-MS950-HKSCS canEncode=false '\u0000' - '\u007f'

(This is a part of the fix for 5065777)

###@###.### 2004-06-22