pg_controldata output documentation

Is there any documentation on the output from pg_controldata? Most of it
seems intuitive but I would like something definitive on the following
lines:

Latest checkpoint location:           2F9/B38DE758
Prior checkpoint location:            2F9/A3F688F8
Latest checkpoint's REDO location:    2F9/B38DE758
Latest checkpoint's UNDO location:    0/0

Especially, how do I relate this to the file names in the pg_xlog directory.

Thanks ...

Andy

PS - we're relative newbies but getting there
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Andrew Rost
National Operational Hydrologic Remote Sensing Center (NOHRSC)
National Weather Service, NOAA
1735 Lake Dr. West, Chanhassen, MN 55317-8582
Voice: (952)361-6610 x 234
Fax: (952)361-6634
andy.rost@noaa.gov
http://www.nohrsc.noaa.gov
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