DT_DESCRIBES_OPTIONAL
if (!Value && (Info->Flags & DT_DESCRIBES_OPTIONAL))
{ACPI_DMT_UINT16, ACPI_DBG20_OFFSET (OemDataLength), "OEM Data Length", DT_DESCRIBES_OPTIONAL},
{ACPI_DMT_UINT16, ACPI_DBG20_OFFSET (OemDataOffset), "OEM Data Offset", DT_DESCRIBES_OPTIONAL},