ANSI Common Lisp 22 Printer 22.1 The Lisp Printer 22.1.3 Default Print-Object Methods
188.8.131.52 Printing Characters
When printer escaping is disabled,
a character prints as itself;
it is sent directly to the output stream.
When printer escaping is enabled,
then #\ syntax is used.
When the printer types out the name of a character,
it uses the same table as the #\ reader macro would use;
therefore any character name that is typed out
is acceptable as input (in that implementation).
If a non-graphic character has a standardized name5,
that name is preferred over non-standard names
for printing in #\ notation.
For the graphic standard characters,
the character itself is always used
for printing in #\ notation - even if
the character also has a name5.
For details about the #\ reader macro, see Section 184.108.40.206 Sharpsign Backslash.