- <tt>^[yYnN<extra>]</tt>, without 0 and 1 and without
- trailing "<tt>.*</tt>".</p>
+ <tt>^[yY<extra>]</tt> and <tt>^[nN<extra>]</tt>,
+ without 0 and 1 and without trailing "<tt>.*</tt>". The
+ reason is to make sure the expressions have the same form as
+ the expressions used in the C/POSIX locale (<tt>^[yY]</tt> and
+ <tt>^[nN]</tt>).</p>