flashback log,redo log,undo三者之间关系

一直没弄清闪回操作时flashback log与redo log,undo之间的关系。
在网上搜了一把，相关内容整理如下：
1.闪回恢复与闪回日志flashback log有关而闪回查询只和undo有关。
2.oracle10g的flashback有很多种方式，如：flashback drop、flashback database、flashback table等等，和ARCHIVELOG和REDOLOG无关。
3.下在这段原话貌似很重要，可本人英语太烂，一知半解。
Flashback Table, Flashback Query, Flashback Transaction Query and Flashback Version
Query all rely on undo data, records of the effects of each update to an Oracle database
and values overwritten in the update. Used primarily for such purposes as providing
read consistency for SQL queries and rolling back transactions, these undo records
contain the information required to reconstruct data as it stood at a past time and all
changes since that time.

Flashback Drop is built around a mechanism called the Recycle Bin, which Oracle
uses to manage dropped database objects until the space they occupied is needed to
store new data.

At the physical level, Oracle Flashback Database provides a more efficient direct
alternative to database point-in-time recovery. If you have datafiles which merely have
unwanted changes, then you can use Flashback Database to cause your current
datafiles revert to their contents at a past time. The end product is much like the result
of a point-in-time recovery, but is generally much faster because it does not require
restoring datafiles from backup, and requires only limited application of redo
compared to media recovery.

Flashback Database uses flashback logs to access past versions of data blocks, as well
as some information from the archived redo log. Flashback Database requires that you
configure a flash recovery area for your database, because the flashback logs can only
be stored there. Flashback logging is not enabled by default. Space used for flashback
logs is managed automatically by the database, and balanced against space required
for other files in the flash recovery area.