<p>Most mechanisms are only available on selected platforms, where the
underlying platform and <glossary>APR</glossary> support it. Mechanisms
- which aren't avaiable on all platforms are <em>posixsem</em>,
+ which aren't available on all platforms are <em>posixsem</em>,
<em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
<em>flock</em>, and <em>file</em>.</p>