I use two apps which require a persistent notification: (1) the Pebble Smartwatch app, and (2) Tasker. When I pull down the notification bar (see screenshot), I see both notifications. However, only the Tasker one shows an icon when the notification bar is hidden, and likewise only Tasker shows a slot on my lock screen.
What is the difference between how these apps are showing their persistent notification? From my understanding, if an app wants to run continuously, it MUST put a persistent notification on the notification bar. But somehow the Pebble app is not requiring an icon or displaying on my lock screen.