I beg your pardon, I thought you meant one you'd written privously, not one you wrote today. Please ignore my writing on why you want more than one internal representation. So why not just do this in 2 phases. Use the UTF-16 private space until more CJK glyphs get added into UTF-16 properly, you can then alter the encoding transforms from Asian encodings to pick the new CJK glyph. The only annoying thing here is that ELisp programming that cares about those kinds of characters would break down. Another possible alternative might be: (from the Unicode FAQ) "For a particular implementation, if someone really, really wanted a representation that encoded more characters in a series of 16-bit code units then a series of private-use characters would work. For example, suppose you use a representation that consisted one BMP private-use character followed by one private-use surrogate pair (e.g. three 16-bit units). With such a representation, you can encode 6400 x 131,072 ( = 838,860,800) private use code points." This doesn't sound like the Unicode technical report I mentioned in my other email. Could you explain what you mean here? Thanks, Bill