struct SECURITY_QUALITY_OF_SERVICE

typedef struct _SECURITY_QUALITY_OF_SERVICE
{
     ULONG Length;
     SECURITY_IMPERSONATION_LEVEL ImpersonationLevel;
     UCHAR ContextTrackingMode;
     UCHAR EffectiveOnly;
} SECURITY_QUALITY_OF_SERVICE, *PSECURITY_QUALITY_OF_SERVICE;

Windows Vista Kernel Structures