The original documentation link is broken, and I couldn't find an equivalent page in the docs from a quick look around, but I did find this post, which seems to explain its utility well.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
The original documentation link is broken, and I couldn't find an equivalent page in the docs from a quick look around, but I did find this post, which seems to explain its utility well.