There is a note Init.ora Parameter "_FIX_CONTROL" [Hidden] Reference Note [ID 567171.1]
on My Oracle Support that not only explains the role of the hidden parameter but also
contains references to known bugs in different versions where
the parameter controls fixes.
A full list of bugs and their status (OFF or ON: column VALUE - 0 or 1)
for system and session level (for current session) can be found
in V$SYSTEM_FIX_CONTROL and V$SESSION_FIX_CONTROL views
but value in BUGNO is not the same as it mentioned in a note
where fix control change provided.
Let's say note
Bug 10160615 ORA-1461 from MERGE / UPDATE which sets a LOB column to a long BIND value
has workaround to change status for "_fix_control"=6990305
but search for bug 6990305 on MOS forwarded to another note
Bug 6990305: WRONG COSTING AND PLAN AFTER UPGRADE TO 10.2.0.4.0
which has another fix control number.
Definitely periodic review of My Oracle Support knowledge base
should be one of the DBA routine tasks and to ease it I hope one day support
will come with RSS feature for bugs based on tags of the interest and product areas.
Have a good day!