#ifndef _NTRTL_H
#if (PHNT_MODE == PHNT_MODE_KERNEL || PHNT_VERSION >= PHNT_WIN8)
NTSYSAPI
VOID
NTAPI
RtlClearBit(
_In_ PRTL_BITMAP BitMapHeader,
_In_range_(<, BitMapHeader->SizeOfBitMap) ULONG BitNumber
);
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This function is documented in Windows Driver Kit.