How to enable SQL markup

SQL> conn /as sysdba (or any user)

SQL> set markup html on spool on

SQL> spool db_info.html

SQL> SET echo on

SQL> select COMP_NAME,VERSION,STATUS from dba_registry;

SQL> show PARAMETER

SQL> select * from v$resource_limit;

SQL> select OWNER,OBJECT_NAME,OBJECT_TYPE from dba_objects where STATUS<>'VALID';

SQL> spool off

SQL> set markup html off