EFI_ACPI_6_0_NFIT_GUID_NVDIMM_BLOCK_DATA_WINDOW_REGION

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
extern (C)
enum EFI_ACPI_6_0_NFIT_GUID_NVDIMM_BLOCK_DATA_WINDOW_REGION = GUID(0x91AF0530, 0x5D86, 0x470E, 0xA6, 0xB0, 0x0A, 0x2D, 0xB9, 0x40, 0x82, 0x49);

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