When symbols are read by Common Lisp they are converted to upper case. Note carefully that this remark applies to the characters in symbols. The characters in strings are not converted upper case.
To type a symbol containing lower case characters you can enclose the symbol
in vertical bars, as in
|AbC| or you can put a ``backslash'' before each
lower case character you wish to preserve, as in
A\bC are two different ways of writing the same symbol (just like 2/4
and 1/2 are two different ways of writing the same rational and 123 and 0123
are two different ways to write the same natural number). The symbol has
three characters in its name, the middle one of which is a lower case b.