NtEnumerateTransactionObject - NtDoc

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

NTSYSCALLAPI
NTSTATUS
NTAPI
NtEnumerateTransactionObject(
    _In_opt_ HANDLE RootObjectHandle,
    _In_ KTMOBJECT_TYPE QueryType,
    _Inout_updates_bytes_(ObjectCursorLength) PKTMOBJECT_CURSOR ObjectCursor,
    _In_ ULONG ObjectCursorLength,
    _Out_ PULONG ReturnLength
    );

#endif
#endif

View code on GitHub
#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwEnumerateTransactionObject(
    _In_opt_ HANDLE RootObjectHandle,
    _In_ KTMOBJECT_TYPE QueryType,
    _Inout_updates_bytes_(ObjectCursorLength) PKTMOBJECT_CURSOR ObjectCursor,
    _In_ ULONG ObjectCursorLength,
    _Out_ PULONG ReturnLength
    );

#endif

View code on GitHub

This function is documented in Windows Driver Kit here and here.