The TAPE_GET_MEDIA_PARAMETERS structure describes the tape in the tape drive.
typedef struct _TAPE_GET_MEDIA_PARAMETERS { // tgmp
LARGE_INTEGER Capacity;
LARGE_INTEGER Remaining;
DWORD BlockSize;
DWORD PartitionCount;
BOOLEAN WriteProtected;
} TAPE_GET_MEDIA_PARAMETERS;
The GetTapeParameters function fills the Remaining and Capacity members with estimates of the tape remaining in the current tape partition and the total capacity of the current tape partition.