[This is preliminary documentation and subject to change.]
To inform clients of the data broadcasts available on a network, broadcasts must be preceded by an announcement. An announcement is a small datagram containing information about the upcoming broadcast.
Announcements are sent on publicly known addresses. These addresses are stored in the registry under HKEY_LOCAL_MACHINE/Software/Microsoft/TV Services/Announcements. Up to six Internet Protocol (IP) addresses can be stored under this key.