Thanks Martin and Xiang. Wikipedia is not a reliable source, but it usually is based on reliable sources. In this case seems it is wrong.

The next question is about parameter name. The Wikipedia uses the name "grave accent", the manpage of FreeBSD uuencode uses the name "backquote", the proposed patch uses the name "backtick". "Grave accent" is an official Unicode name, "backquote" and "backtick" are commonly used in programming context. We could use also the name containing "space" with the default value True.