rwm: unavailable is first/only event if sent

 protocol/river-window-management-v1.xml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/protocol/river-window-management-v1.xml b/protocol/river-window-management-v1.xml
index eacdabb..c8fbbaa 100644
--- a/protocol/river-window-management-v1.xml
+++ b/protocol/river-window-management-v1.xml
@@ -46,6 +46,9 @@
         running. The circumstances causing this event to be sent are compositor
         policy.
 
+        If sent, this event is guaranteed to be the first and only event sent by
+        the server.
+
         The server will send no further events on this object. The client should
         destroy this object and all objects created through this interface.
       </description>