History List Icon on Vivoactive HR

On my Vivoactive HR, when I select "History" on the watch's menu, I'm shown a list of recorded activities that are stored on the watch.
The Garmin apps (running, walking etc) show an icon next to their respective entries.
My app shows a circle with 3 dots in it.
I've searched the documentation and find no indication of how I can specify an icon when building my app, so that an icon appears in this list.
Can anyone tell me if I can specify an icon for display in the history list, and if so, how ?
Thanks