Member Rara Avis
The search at the main site is an earlier version of our own Smart Search, and follows pretty much the same rules set. Specifically (from the QuickView in Smart Search) :
Only words or phrases containing an upper case character will be treated as case sensitive. A search on "usa" will match "Usa", "USA", and "usA", while the term "USA" matches only its uppercase version. When in doubt, it is always better to use lowercase search terms.