LdrUnregisterDllNotification - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTLDR_H
#if (PHNT_MODE != PHNT_MODE_KERNEL)
// begin_msdn:"DLL Load Notification"
#if (PHNT_VERSION >= PHNT_VISTA)

NTSYSAPI
NTSTATUS
NTAPI
LdrUnregisterDllNotification(
    _In_ PVOID Cookie
    );

#endif
// end_msdn
#endif
#endif

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This function is documented in Windows SDK.