What Does the Zw Prefix Mean?
The Windows native system services routines have names that begin with the prefixes Nt and Zw. The Nt prefix is an abbreviation of Windows NT, but the Zw prefix has no meaning. Zw was selected partly to avoid potential naming conflicts with other APIs, and partly to avoid using any potentially useful two-letter prefixes that might be needed in the future.
Many of the Windows driver support routines have names that begin with two- or three-letter prefixes. These prefixes indicate which kernel-mode system components implement the routines. The following table contains some examples.
| Prefix | Kernel component | Example routine |
|---|---|---|
Cm |
Configuration manager |
|
Ex |
Executive |
|
Hal |
Hardware abstraction layer |
|
Io |
I/O manager |
|
Ke |
Kernel core |
|
Mm |
Memory manager |
|
Ob |
Object manager |
|
Po |
Power manager |
|
Tm |
Transaction manager |
|
Nt and Zw |
Native system services |