The basic characters which are used to build REDUCE symbols are the following:
With the exception of strings and characters preceded by an exclamation mark, the case of characters is ignored: depending of the underlying LISP they will all be converted internally into lower case or upper case: ALPHA, Alpha and alpha represent the same symbol. Most implementations allow you to switch this conversion off. The operating instructions for a particular implementation should be consulted on this point. For portability, we shall limit ourselves to the standard character set in this exposition.