#ifndef _NTPSAPI_H
// User processes and threads
#if (PHNT_MODE != PHNT_MODE_KERNEL)
#if (PHNT_VERSION >= PHNT_VISTA)

typedef NTSTATUS (NTAPI *PUSER_THREAD_START_ROUTINE)(
    _In_ PVOID ThreadParameter
    );

#endif
#endif
#endif
View code on GitHub

#ifndef _NTRTL_H

// Threads

typedef NTSTATUS (NTAPI *PUSER_THREAD_START_ROUTINE)(
    _In_ PVOID ThreadParameter
    );

#endif
View code on GitHub