With the introduction of UTF-8 support in the client driver (
DERBY-728), the documentation regarding the length of the arguments (RDBNAM, USRID, etc) will become misleading.
On the list, Kathey has identified  one of such spots. Before releasing, we should try to find any other occurrences and fix them accordingly. Please note that the UTF-8 is a variable length encoding and as such, since we are maintaining the 255-byte length cap, the length in characters will now be variable.
Regular ASCII characters still take 1 byte, Latin and other extended characters take 2 bytes, Chinese characters take 3 bytes and some special characters take 4 bytes. 
 - http://old.nabble.com/Database-name-length-tt29691419.html
 - http://www.utf8-chartable.de/