Document deferred eventcb behaviour

diff --git a/include/event2/bufferevent.h b/include/event2/bufferevent.h
index 513d32854865adefb0375f383785a11375c9b5ee..f3cf1d6ef21e6456778a2c31ecf7ab7160002b34 100644 (file)
--- a/include/event2/bufferevent.h
+++ b/include/event2/bufferevent.h
@@ -138,6 +138,9 @@ typedef void (*bufferevent_data_cb)(struct bufferevent *bev, void *ctx);
    The event callback is triggered if either an EOF condition or another
    unrecoverable error was encountered.
 
+   For bufferevents with deferred callbacks, this is a bitwise OR of all errors
+   that have happened on the bufferevent since the last callback invocation.
+
    @param bev the bufferevent for which the error condition was reached
    @param what a conjunction of flags: BEV_EVENT_READING or BEV_EVENT_WRITING
          to indicate if the error was encountered on the read or write path,