The altitude the class's system driver should use.
int SetAltitude(int iAltitude);
INT SetAltitude(INT iAltitude);
This property specifies the altitude that the class's system driver should use. 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's documentation is unclear about how altitudes should be chosen for process manager filter drivers; please refer to the Driver Altitudes topic for more information. The default value of this property is 400055 (which isn't registered with Microsoft), but applications can likely choose any value they desire. If the specified altitude is already in use by another driver, the class's driver will behave in the manner specified by the StrictAltitude property.