In “ALTER SYSTEM” one can include a comment which gets recorded in the spfile and also in v$parameter as shown below. It can be used to record why parameter was changed.

Example:
SQL> alter system set open_cursors=1000 comment='07-Jan-2012 Changed AJ needed for application XYZ';

SQL> select value, update_comment from v$parameter where name = 'open_cursors';

VALUE
——————————————————————————–
UPDATE_COMMENT
——————————————————————————–
400

$ strings spfileTESTDB.ORA | grep open_cursors
*.open_cursors=400#07-Jan-2012 Changed AJ needed for application XYZ