Be less wishy-washy in the documentation and comments about whether a

ParameterStatus message can be sent during COPY OUT: it's definitely
possible, since COPY from a SELECT subquery can trigger any user-defined
function.

doc/src/sgml/protocol.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.71 2008/01/14 18:46:17 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.72 2008/01/15 22:18:20 tgl Exp $ -->
 
 <chapter id="protocol">
  <title>Frontend/Backend Protocol</title>
@@ -1044,10 +1044,10 @@
    </para>
 
    <para>
-    It is possible for NoticeResponse messages to be interspersed between
-    CopyData messages; frontends must handle this case, and should be
-    prepared for other asynchronous message types as well (see <xref
-    linkend="protocol-async">).  Otherwise, any message type other than
+    It is possible for NoticeResponse and ParameterStatus messages to be
+    interspersed between CopyData messages; frontends must handle these cases,
+    and should be prepared for other asynchronous message types as well (see
+    <xref linkend="protocol-async">).  Otherwise, any message type other than
     CopyData or CopyDone may be treated as terminating copy-out mode.
    </para>
 

src/interfaces/libpq/fe-protocol3.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.32 2008/01/14 18:46:17 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.33 2008/01/15 22:18:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1310,9 +1310,8 @@ getCopyDataMessage(PGconn *conn)
 		/*
 		 * If it's a legitimate async message type, process it.  (NOTIFY
 		 * messages are not currently possible here, but we handle them for
-		 * completeness.  NOTICE is definitely possible, and ParameterStatus
-		 * could probably be made to happen.)  Otherwise, if it's anything
-		 * except Copy Data, report end-of-copy.
+		 * completeness.)  Otherwise, if it's anything except Copy Data,
+		 * report end-of-copy.
 		 */
 		switch (id)
 		{