Three detail sections

State clearly that the developer can discover that a frame was paused by UA intervention. Closes #12.

README.md

@@ -24,6 +24,8 @@ if (frameElement.paused)
   alert("The frame is paused");
 ```
 
+
+
 ## Use Cases
 * Pausing frames that violate policies (e.g., [TransferSizePolicy](https://github.com/WICG/transfer-size)). This provides a gentle, yet firm response to misbehaving frames.
 * Pausing resource-intensive frames that the user isn't currently paying attention to. For instance, a carousel of frames, where some of the frames are offscreen.
@@ -32,9 +34,13 @@ if (frameElement.paused)
 ## UX Considerations
 The user is likely to become confused by the frame becoming a static image. E.g., clicking on links won't work. It is therefore advisable that if you pause a visible frame that you (the web developer) make it visually obvious to the user that it's not interactive (e.g., overlay a semi-transparent play button over the paused frame).
 
-## Pausing Details
-When a frame is paused, it (and its child frames which are transitively paused) effectively becomes a static image. Any animated images or media elements pause. No javascript events (e.g., onload, onclick) are fired, no tasks are run, and no default handlers (e.g., navigating on a click) are fired within the paused frame. Instead, the events will be queued. Further, while paused, the frame will not navigate (e.g., meta refresh will not work), CSS animations won't run, and the frame won't render, therefore there are no  `requestAnimationFrame` (rAF) callbacks.
+# Pause Details
+When a frame is paused (either for intervention or via API), the frame and its descendants will increment their new `pausedCounter` member. Any frame whose `pauseCounter` value is greater than zero are paused, and behave like a static image. Any animated images or media elements pause. No future javascript events (e.g., onload, onclick) are fired, no enqueued tasks are run, and no default handlers (e.g., navigating on a click) are fired within the paused frame. Instead, the events will be queued. Further, while paused, the frame will not navigate (e.g., meta refresh will not work), CSS animations won't run, and the frame won't render, therefore there are no  `requestAnimationFrame` (rAF) callbacks.
 
 There are a few times that the frame might need to be rerendered (e.g., on frame resize or the browser dropped a texture while the frame was offscreen). When that happens, the frame will be rendered once, and rAF will correspondingly be called once beforehand.
 
+# Unpause Details
+When a frame is unpaused, it, and its descendants decrement their `pausedCounter` member. If the counter reaches 0 the frame is unpaused. The queues resuming running their tasks and the frame resumes rendering as normal.
 
+# Paused details
+`frameElement.paused` will return true if the frame's `pausedCounter` member is greater than 0. Since frames paused by either the API or UA intervention increment the `pausedCounter` member, it is possible to discover that a frame was paused by the UA. This allows for transparency to developers about the UA's intervention.