BeOS was an attempt to build a new desktop operating system with SMP, multi-threading, and multimedia built in from the beginning. Originally, Be Inc. had their own PowerPC-based hardware. The system was later ported to Apple PowerMac hardware and x86 PCs. The BFS file system used natively by BeOS supports some interesting techniques, for instance search query results are updated live as changes are made to the file system.
The BFS superblock is 512 bytes in size and originally was placed right at the beginning of the partition. For the x86 version, it had to be moved to the second sector to make room for boot code. The file system uses each platform's native byte order.
QNX RTOS is a POSIX-compatible real-time operating system based on a micro-kernel. Its current file system was dubbed QNX4 probably because it appeared in that version of the OS. It is unique in that it has no real superblock, just four inode structures describing the root directory, the inode file, and two alternative boot codes. This "superblock" is located in the second sector, i.e. 512 bytes into the device.
The "magic value" disktype looks for is actually the string "/", the file name of the root directory. At this time, only the basic signature check is done.