Expand/clarify "single pointer" definition

guidelines/terms/21/single-pointer.html

@@ -3,7 +3,8 @@
 
    <p class="change">new</p>
 
-   <p>pointer input that operates with one point of contact with the screen, including single taps and clicks, double-taps and clicks, long presses, and path-based gestures</p>
+   <p>A single pointer operation involves the use of a single <a>pointer input</a>, such as a mouse, or a single finger or stylus on a touchscreen. Single pointer operations include taps and clicks, double-taps and clicks, long presses, and dragging.</p>
+   <p>Note: Pointer Events [[!pointerevents]] define a pointer as a hardware agnostic representation of input devices that can target a specific coordinate (or set of coordinates) on a screen, such as a mouse, pen, or touch contact.</p>
 
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