NtNotifyChangeDirectoryFileEx - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTIOAPI_H
#if (PHNT_VERSION >= PHNT_REDSTONE3)

NTSYSCALLAPI
NTSTATUS
NTAPI
NtNotifyChangeDirectoryFileEx(
    _In_ HANDLE FileHandle,
    _In_opt_ HANDLE Event,
    _In_opt_ PIO_APC_ROUTINE ApcRoutine,
    _In_opt_ PVOID ApcContext,
    _Out_ PIO_STATUS_BLOCK IoStatusBlock,
    _Out_writes_bytes_(Length) PVOID Buffer,
    _In_ ULONG Length,
    _In_ ULONG CompletionFilter,
    _In_ BOOLEAN WatchTree,
    _In_opt_ DIRECTORY_NOTIFY_INFORMATION_CLASS DirectoryNotifyInformationClass
    );

#endif
#endif

View code on GitHub
#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwNotifyChangeDirectoryFileEx(
    _In_ HANDLE FileHandle,
    _In_opt_ HANDLE Event,
    _In_opt_ PIO_APC_ROUTINE ApcRoutine,
    _In_opt_ PVOID ApcContext,
    _Out_ PIO_STATUS_BLOCK IoStatusBlock,
    _Out_writes_bytes_(Length) PVOID Buffer,
    _In_ ULONG Length,
    _In_ ULONG CompletionFilter,
    _In_ BOOLEAN WatchTree,
    _In_opt_ DIRECTORY_NOTIFY_INFORMATION_CLASS DirectoryNotifyInformationClass
    );

#endif

View code on GitHub

This function is documented in Windowd Driver Kit.