If your client has issued a property request to another client, and that client has in turn answered it by sending a TX_PROP_ANNOUNCE message, your client will receive an RX_PROP_ANNOUNCE message.
Even if your client has not requested another client's property, your client may still receive property announcements from parties that want you to know anyway. For example, a friend's client may be announcing to you that he has just gotten on-line. What to do with unsolicited property announcements is entirely up to your client.
The format for an RX_PROP_ANNOUNCE message is:
RX_PROP_ANNOUNCE address property_and_value
where
| address | is the (apparent) identity of the announcing client and |
| property_and_value | is an envelop whose data field names a property and its value. |
The contents of property_and_value are the same as described for TX_PROP_ANNOUNCE.