User blog comment:Cristina7/Introducing Discussions, a New Platform For Engaging Your Community/@comment-452-20160908160900/@comment-5275700-20160928184358

At this time, they cannot be. The current Notifications system is tied to Forum and Message Wall features specifically. One of the next projects is an updated API-based Notifications system (service). This will include highlight-type functionality that should be even more versatile than what we currently offer. I use the phrase "highlight-type" only because we may use a different term for this function.