The other day I was checking some settings in Opera 7.25 for Sharp/Cacko.
I found 2 useful sites on Opera settings.
http://www.opera.com/support/usingopera/operaini/index.dml
http://www.mobileopera.com/opera5/
To display complete global history, type the following into the address bar and hit Enter.
opera:history
To access the address bar use the 'G' key on the keyboard.
After using Opera for about 6 days, I noticed the history listing was getting very long.
I now have a long list of all sites visited in the last 6 days.
I wanted to delete it, so I used these instructions found at second link above.
I just changed the path info, that which is on my C3100.
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Navagate to /home/zaurus/.opera/
In this folder find the file global.dat and delete it.
This is a safe method to delete Opera's history list as long as
the browser is closed.

Additionally, vlink4.dat stores a separate list of visited URLs
which isn't available to the user but is used by Opera to
determine which links to render in the 'visited' colour.
This file may also be deleted safely to restore all links to
an 'unvisited' state.
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I discovered that "global.dat" is 14kb
but
vlink4.dat is a whopping 184kb
Both of these files are in the Flash area on my Z, so I decided to delete vlink4.dat,
since it only controls the color of "visited" links.

I hope this helps someone, especially new Zaurus users.
Jon