or download this
changes5.004: Title: "Document $^M in perlvar"
emacs\cperl-mode.el:$^M A buffer for emergency memory allocation w
+hen running out of memory.
...
win32\html\pod\perlvar.html:<dt><strong><a name="item__24_5em">$^M</a>
+</strong><br />
win32\html\pod\perlvar.html:However, if suitably built, Perl can use t
+he contents of <a href="#item__24_5em"><pre>$^M</pre></a>
win32\html\pod\perlvar.html: $^M = 'a' x (1 << 16);</pre>