#ifndef _NTPSAPI_H
// Threads
#if (PHNT_MODE != PHNT_MODE_KERNEL)

#define QUEUE_USER_APC_SPECIAL_USER_APC ((HANDLE)0x1)

#endif
#endif
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This constant defines a special value for ReserveHandle that allows queuing special user-mode APCs.

Applicable to

NtQueueApcThreadEx

Remarks

For the introduction to special user-mode APCs, see this blog post.

Because execution of special APCs is not synchronized with the target thread (which might happen to acquire locks), it is crucial to keep the amount and complexity of the code invoked by the special APC routine to a minimum.

Required OS version

This flag was introduced in Windows 10 RS5 (1809).