#include <blockdev.h>
typedef struct BlockDev_Scatter_Gather{
        ULONG BD_SG_Count;        ; Block count; else byte count if IORF_CHAR_COMMAND set
        ULONG BD_SG_Buffer_Ptr;    
}  _BlockDev_Scatter_Gather     ;
 Contains logical scatter/gather descriptors (SGDs). If (IOR_flags & IORF_SCATTER_GATHER) is true, the IOP's IOR_buffer_ptr field points to a list of these logical SGDs. Note that this (logical) structure is different from the physical SGD structure.
IOR, VRP