Driver Support Routines
http://msdn.microsoft.com/en-us/library/ff544200(v=vs.85)
Ob - Object Manager
Mm - Memory Manager
Ps - Process and Thread Manager Routines
Io - I/O Manager Routines
Po - Power Manager Routines
Cm - Configuration Manager Routines
Tm (and Zw) - Kernel Transaction Manager (KTM) Routines
Se - Security Reference Monitor Routines
Ke - Core Kernel Library Support Routines
Ex - Executive Library Support Routines
Rtl - Run-Time Library (RTL) Routines/Safe String Library Routines/Safe Integer Library Routines
Dma - DMA Library Routines (?)
Hal - HAL Library Routines
Clfs - CLFS Management Library Routines
Zw - ZwXxx Routines
Aux - Auxiliary Kernel-Mode Library Routines and Structures