v$undostat rows

While trying to get some information from v$undostat, I found that the view
has only 576 rows in both our production and test databases. This is
v10.202. However, the 10.2 document says that it has 1008 rows for 7 days:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/dynviews_2174.htm

The 11.1 doc has it as 576 rows:
http://download.oracle.com/docs/cd/B28359_01/server.111/b28320/dynviews_3110.htm

Is this something documentation bug?  i was trying to find out week end
activity, grr..  Too lazy to run awr.

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