Index: skins/native/pipe.c
===================================================================
--- skins/native/pipe.c	(revision 143)
+++ skins/native/pipe.c	(working copy)
@@ -598,7 +598,11 @@
  *
  * @param size The size in bytes of the message (payload data
  * only). Zero is a valid value, in which case the service returns
- * immediately without sending any message.
+ * immediately without sending any message. This parameter allows
+ * you to actually send less data than you reserved using the
+ * rt_pipe_alloc() service, which may be the case if you did not
+ * know how much space you needed at the time of allocation. In all
+ * other cases it may be more convenient to just pass P_MSGSIZE(msg).
  *
  * Additionally, rt_pipe_send() causes any data buffered by
  * rt_pipe_stream() to be flushed prior to sending the message. For