List of hidden parameters in Oracle DB

How to view list of hidden parameters?

Hidden parameters sometimes ease the life of  DBA but be carefull while using them. Oracle usually does not support the usage of hidden parameters without their knowledge and you can't even know the side effects of the parameter.
Here is the query you can use to view the values of hidden parameter.

--List with hidden parameters  -- SYS user with sysdba privileges is requared in order to execute the query.

SELECT a.ksppinm name,
       b.ksppstvl value,
       b.ksppstdf deflt,
       decode(a.ksppity,
              1,
              'boolean',
              2,
              'string',
              3,
              'number',
              4,
              'file',
              a.ksppity) type,
       a.ksppdesc description
  FROM sys.x$ksppi a, sys.x$ksppcv b
 WHERE a.indx = b.indx
   AND a.ksppinm like '\_%' escape '\'
 ORDER by name;