As you know I have just started my own blog and I realized that sometimes pretty simple things can be really handy to know. Some time ago I found out by accident that Oracle 11G database has a nice feature to find out the available underscore parameters in the pfile/spfile (there are more underscore parameters, but these are really dangerous).
=================== DISCLAIMER ===================
The usage of underscore parameters is officially prohibited. Underscore parameters should only be used after having instructions from Oracle Support. The usage from underscore parameters without having these instructions can lead to an unsupported Oracle environment. Also instability, crashes or even corruptions can be caused by usage of these parameters. So please use the information in this post with care.
These parameters can be easily obtained by giving the following command on the sql prompt as shown here: