User Agent String.Com 

User Agent String explained :

Opera 9.61
Opera	Name : Opera
9.61	Browser version
X11	X Window System a windowing system for bitmap displays
Linux x86_64	Operating System: Linux running on a Intel CPU running on a 64 bit processor
U	Security values: N for no security U for strong security I for weak security
fr	Language Tag, indicates the language for which the client had been localized (e.g. menus and buttons in the user interface) fr = French
Presto	Layout engine for Opera
2.1.1	Version 2.1.1
Last visit:	2008.11.12 05:40
All Opera user agent strings