This depends on if the file is being created on a FAT or NTFS partition. The maximum file name length on a NTFS partition is 256 characters, and 11 characters on FAT (8 character name, . , 3 character extension). NTFS file names keep their case, whereas FAT file names have no concept of case (however the case is ignored when performing a search etc on NTFS). There is the new VFAT which also has 256 character file names.
