On Sun, 2 Mar 1997, Hans Aberg wrote: > Actually, what is needed, is a simple extension of the TeX \def command: > \def\name<parameter text>{definition text}[exception text] > If a command somehow is unable to process the parameter text, then the > original input text (before the parsing of the parameter text began) is > left unaffected, and the execution passes to the exception text. > Then stuff like optional commands could be implemented most easily, and > perhaps the stuff you are asking for, too. This sounds for me like an OTP (Omega Translation Process) input filter. With Omega you can do a lot of manipulation (notably character encoding conversion and various more or less complicated character cluster->glyph transformations e.g. for Hebrew or Arabic) of text before TeX sees the text. You can avoid any active characters. Werner