At 18.18 +0100 2001-02-19, jbezos wrote: >> Question raised by this: Can OCPs output control sequences, or do they just >> produce characters? > >They can output any token (IIRC there is a bug >when \input is used, but I'm not sure). In fact, >tokens are necessary when translating Unicode to, >say, OT1. > >>Can one specify what catcode the characters should have? > >Unfortunately not. The catcodes used are the >catcodes when the replacement is done. That means >that "private" names containing @ cannot be >used (in general, or if \csname is used). OK, so in fact the OCPs cannot produce tokens (they just output characters), but that is not really a restriction as long as some character has catcode 0 and \csname (or some disguise of it) is available. (The former condition could be a problem in \verb-like contexts. One would probably have to have a "private escape" character for the OCPs.) On the other side of things, how does Omega handle "lost character" conditions? The current TeX behaviour of ignoring the character and possibly putting an info message in the log file could certainly be improved ... When one is typesetting normal text the approriate action would be (a) substitution with a character from another font (LaTeX can do this for characters are represented by encoding-specific commands, but there are no such mechanisms in TeX for explicit character tokens), (b) an error message, or (c) a combination of the two. When one is typesetting verbatim (or verbatim-like) text however, the priorities are different. In particular, I would like to have some recourse to (d): Typeset a suitable representation (e.g. U+0312, in a suitably distinct font) of the Unicode for the character. Lars Hellström