-<p>Throughout this manual, the term "right-click" refers to the act of pressing and releasing the rightmost mouse button (technically the button that is identified as button number 3 - your operating system may allow this be reassigned). This action is used to pop up "context menus" (hence the term "context click", which you will also see). It is also used by default in combination with the shift key for deleting objects within the editor window.</p>
+<p>
+ The term <dfn>right-click</dfn> refers to the act of pressing and releasing
+ the rightmost mouse button (internally called <kbd class="mouse">Button2</kbd>,
+ but again your operating system may allow this to be reassigned).
+ This action is used to pop up <dfn>context menus</dfn> (hence the term
+ "context click", which you will also see). It is also used by default in
+ combination with the shift key to delete objects within the editor
+ window.
+</p>
+<p class="note mac">
+ Mac OS mice sometimes have only one button. On Mac OS if you press and hold
+ the Control key this is equivalent to right-clicking.
+</p>
+
+<h2>Middle Clicking</h2>
+<p>
+ A <dfn>middle-click</dfn> refers to the act of pressing and releasing the
+ middle mouse button (<kbd class="mouse">Button3</kbd>, which may also be
+ reassigned). Not all all mice have a middle click button
+ (see the <a href="/setting-up-your-system/mouse/">Mouse</a> chapter for
+ details). Sometimes the scroll wheel acts as a clickable middle button.
+ This action is used for time-constrained region copying and mapping MIDI
+ bindings.
+</p>
+