Is "IF EXISTS" legit in "ALTER TABLE ... RENAME"?

According to the PG 9.1 doc (http://www.postgresql.org/docs/current/static/sql-altertable.html), this is a valid flavor of ALTER TABLE:

ALTER TABLE [ IF EXISTS ] name   RENAME TO new_name

But when I try to execute such a command, I get:

ERROR:  syntax error at or near "EXISTS"
LINE 1: ALTER TABLE IF EXISTS event
                       ^
QUERY:  ALTER TABLE IF EXISTS event
    RENAME TO event_s;
CONTEXT:  PL/pgSQL function "convert_table_to_history" line 60 at EXECUTE statement

As you'll see, in this case the command was issued from a function.  But issuing it directly evokes the same error.

?!?

~ Thanks in advance

~ Ken