File System Development Kit -
Makes it easier to write installable file systems for Windows NT.
You implement your on-disk structure; they worry about dealing with
the cache, the disk class drivers, and so on. Includes consulting and
support services.
File Systems Filter Driver Kit -
Helps you write a driver that installs "above" the file system drivers. Intercept and change the behavior of file open, etc., requests.
Kernel Mode Sockets Interface -
Allows your kernel-mode driver to make and accept connections using the
IP, IPX/SPX, and NetBEUI transport layers.
OSR DDK -
Driver debugging and troubleshooting support library