dwIoControlCode

[in] Specifies this IOCTL.

lpInBuffer

[in] Pointer to a DWORD containing the region index to format. Alternatively, pass NULL to format all regions.

nInBufferSize

[in] Size of a DWORD when formatting a single region. Set to zero (0) when formatting the entire store.

lpOutBuffer

Not used. Set to NULL.

nOutBufferSize

Not used. Set to zero (0).

lpBytesReturned

Not used. Set to NULL.

Returns a nonzero value if successful. If this IOCTL fails, the return value is zero. To obtain extended error information, call GetLastError.

Reference