Was looking around in “settings” on the iPod Touch when I came across the screen below. It lists all the location based services (LBS) that are on the device. Each of the services listed is looking for location data when you use their service. It finally came to my attention what the purple arrow means. When it appears it means that an app has requested location data within the past 24 hours. Was just in the Yelp app previous to visiting this screen, hence the location data indicator was on.