The SQL:2003 page is correct.   
 MERGE was an Optional component in the SQL:2003 Foundation standard, as noted in Oracle 10g Database SQL Reference documentation [here|http://docs.oracle.com/cd/B13789_01/server.101/b10759/ap_standard_sql001.htm#g15079] where 10g partially supports Optional Feature F312 - MERGE statement. 
 MERGE was updated for SQL:2008, as noted in Oracle 11g Database SQL Reference documentation [here|http://docs.oracle.com/cd/E14072_01/server.112/e10592/ap_standard_sql004.htm] where 11g does not support some of the newer clauses. 

 I am updating the MERGE page appropriately.