How do Campus Announcements announcement group preferences work?

Campus Announcements channel preferences default to opting-in to receiving announcements directed at the groups of which a user is a member at the time the user first views the channel.

Campus Announcements includes a feature whereby end users can express a preference as to which groups they would like to be considered members of for purposes of determining which campus announcements are displayed. These preferences are fundamentally opt-in preferences, whereby among all the groups of which a user is a member, the user selects zero, some, or all of them to subscribe to in the context of this channel.

The Campus Announcements channel creates and persists these preferences the first time a user renders the channel and from that point forward Campus Announcements honors those preferences for that user. The preferences are created and stored whether the user interacts with the channel's "edit preferences" screen or not.

The preferences default to choosing to opt-in to all groups of which the user is a member at the time the preferences are created.

For example, if the user Bruce Sherman is a member of the group Huddled Masses before first viewing this channel, he will see any announcements directed at the Huddled Masses group by default. However, if later he becomes a member of the group Privileged Few, he will not by default see announcements directed to the group Privileged Few. Becoming a member of a group makes the group available for subscription (for "opt-in") via the Campus Announcements channel preferences. If Bruce then enters the channel preferences panel and selects the Privileged Few group, he will begin seeing announcements directed at Privileged Few. If Bruce de-selects the Huddled Masses group, he will stop seeing announcements directed at that group (and not also at another group he has opted-into).