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//0x20 bytes (sizeof)
struct _SUBSECTION
{
    struct _CONTROL_AREA* ControlArea;                                      //0x0
    struct _MMPTE* SubsectionBase;                                          //0x4
    struct _SUBSECTION* NextSubsection;                                     //0x8
    ULONG PtesInSubsection;                                                 //0xc
    union
    {
        ULONG UnusedPtes;                                                   //0x10
        struct _MM_AVL_TABLE* GlobalPerSessionHead;                         //0x10
    };
    union
    {
        ULONG LongFlags;                                                    //0x14
        struct _MMSUBSECTION_FLAGS SubsectionFlags;                         //0x14
    } u;                                                                    //0x14
    ULONG StartingSector;                                                   //0x18
    ULONG NumberOfFullSectors;                                              //0x1c
};