Operators live in namespaces. CREATE/DROP/COMMENT ON OPERATOR take

qualified operator names directly, for example CREATE OPERATOR myschema.+
( ... ).  To qualify an operator name in an expression you need to write
OPERATOR(myschema.+) (thanks to Peter for suggesting an escape hatch).
I also took advantage of having to reformat pg_operator to fix something
that'd been bugging me for a while: mergejoinable operators should have
explicit links to the associated cross-data-type comparison operators,
rather than hardwiring an assumption that they are named < and >.

src/include/parser/parse_func.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parse_func.h,v 1.39 2002/04/11 20:00:15 tgl Exp $
+ * $Id: parse_func.h,v 1.40 2002/04/16 23:08:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -28,16 +28,6 @@ typedef struct _InhPaths
 	Oid		   *supervec;		/* vector of superclasses */
 } InhPaths;
 
-/*
- *	This structure holds a list of possible functions or operators that
- *	agree with the known name and argument types of the function/operator.
- */
-typedef struct _CandidateList
-{
-	Oid		   *args;
-	struct _CandidateList *next;
-}	*CandidateList;
-
 /* Result codes for func_get_detail */
 typedef enum
 {