{ expr { = | != | ^= | <> | > | < | >= | <= } 
  { ANY | SOME | ALL } { expr_list | ( subquery ) }
| expr_list { = | != | ^= | <> }
  { ANY | SOME | ALL } { (expr_list [, expr_list]...) | ( subquery ) }
}

For information on the symbols and conventions of Backus-Naur Form (BNF) syntax, see Appendix A.