请教IRP_MJ_READ 和 IRP_MJ_WRITE IO偏移的问题

WDK中关于IRP_MJ_READ有如下描述：
Pointer to a LARGE_INTEGER variable that specifies the starting byte offset within the file of the data to be read.
Under certain circumstances, this parameter might validly contain a NULL or negative value. For example, if the file object was opened for synchronous I/O, and one of the following conditions is true, this indicates that the current file position should be used instead of an explicit file offset value:

IrpSp->Parameters.Read.ByteOffset == NULL

IrpSp->Parameters.Read.ByteOffset.LowPart == FILE_USE_FILE_POINTER_POSITION and IrpSp->Parameters.Read.ByteOffset.HighPart == -1.


WDK中关于IRP_MJ_WRITE有如下描述：
A pointer to a LARGE_INTEGER variable that specifies the starting byte offset within the file of the data to be written.
Under certain circumstances, this parameter might validly contain a NULL or negative value. For example:

If the following condition is true, this indicates that the current end of file should be used instead of an explicit file offset value:
IrpSp->Parameters.Write.ByteOffset.LowPart == FILE_WRITE_TO_END_OF_FILE and IrpSp->Parameters.Write.ByteOffset.HighPart == -1

If the file object was opened for synchronous I/O, and one of the following conditions is true, this indicates that the current file position should be used instead of an explicit file offset value:
IrpSp->Parameters.Write.ByteOffset == NULL

IrpSp->Parameters.Write.ByteOffset.LowPart == FILE_USE_FILE_POINTER_POSITION and IrpSp->Parameters.Write.ByteOffset.HighPart == -1


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其中有IrpSp->Parameters.Read.ByteOffset == NULL和IrpSp->Parameters.Write.ByteOffset == NULL，
可结构中IrpSp->Parameters.xxx.ByteOffset 并不是指针，请问是WDK上写错了吗？

如果是WDK写错了，那么关于IrpSp->Parameters.Write.ByteOffset == NULL的情况，正确的应该是怎样呢？
如果没有写错，请问该怎么理解呢？

NULL = 0

IrpSp->Parameters.Read.ByteOffset == NULL或者
IrpSp->Parameters.Read.ByteOffset == 0 编译通不过，
IrpSp->Parameters.Read.ByteOffset 是个结构体。

如果IrpSp->Parameters.Read.ByteOffset == NULL时，也就是
IrpSp->Parameters.Read.ByteOffset .QuadPart  == 0 ，这个哪儿有文档可循呢？

ByteOffset 是不个LargerInteger

ByteOffset 是联合体 LARGE_INTEGER

包含两个结构体和一个LONGLONG类型

#if defined(MIDL_PASS)
typedef struct _LARGE_INTEGER {
#else // MIDL_PASS
typedef union _LARGE_INTEGER {
    struct {
        ULONG LowPart;
        LONG HighPart;
    } DUMMYSTRUCTNAME;
    struct {
        ULONG LowPart;
        LONG HighPart;
    } u;
#endif //MIDL_PASS
    LONGLONG QuadPart;
} LARGE_INTEGER;

IrpSp->Parameters.Read.ByteOffset == NULL 的意思是
IrpSp->Parameters.Read.ByteOffset .QuadPart  == 0 吗？