SQL> insert into T ( ID ) values ( null )
CON> returning ( ID );

          ID
============
          10

SQL> insert into T ( ID ) values ( null )
CON> returning ( ID, VAL );
Statement failed, SQLSTATE = 42000
Dynamic SQL Error
-SQL error code = -104
-Token unknown - line 2, column 15
-,

SQL> insert into T ( ID ) values ( null )
CON> returning ID, VAL;

          ID VAL
============ ==========
          11 STR # 11

SQL> insert into T ( ID ) values ( null )
CON> returning ( ID ), ( VAL );

          ID VAL
============ ==========
          12 STR # 12