How to Find out Undocumented Paramaters in Oracle Database

Use following SQL Query to find out Undocumented paramater and their value.

SELECT xpi.ksppinm "Parameter Name",
xpi.ksppdesc "Description",
xcv.ksppstvl "Session Value",
xsv.ksppstvl "Instance Value"
FROM x$ksppi xpi,
x$ksppcv xcv,
x$ksppsv xsv
WHERE xpi.indx = xcv.indx
AND xpi.indx = xsv.indx
AND SUBSTR (xpi.ksppinm, 1, 1) ='_'
ORDER BY xpi.ksppinm;