Altitude Property

The altitude the class's system driver should use when operating in minifilter mode.


int GetAltitude();
int SetAltitude(int iAltitude);
INT GetAltitude();
INT SetAltitude(INT iAltitude);

Default Value



This property specifies the altitude that the class's system driver should use when operating in minifilter mode (i.e., when the FilterMode property is set to FS_FILTER_MODE_MINIFILTER). A driver's altitude determines its absolute position in the stack of filter drivers; drivers with higher altitudes are attached towards the top of the stack, closer to user mode, which allows them to process requests earlier.

Microsoft manages and assigns filesystem minifilter driver altitudes directly, so an application-specific altitude value must be obtained from Microsoft before an application is deployed in production. Please refer to the Driver Altitudes topic for more information. During development, an appropriate arbitrary value, such as 360000 (which isn't registered with Microsoft), can be used.

If this property is queried before an altitude has been set (via this property or the Install method), it will return -1.

Note: This property cannot be changed when Active is true. Additionally, the Initialize method must be called before attempting to get or set this property's value, which is stored in the registry.

This property is not available at design time.

Data Type


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CBFS Filter 2020 C++ Edition - Version 20.0 [Build 7836]