IMS DB/DC Online Skills Assessment Test

James has just written a new program following your advice to use checkpoints but now he is faced with another problem. After issuing a checkpoint, the program seems to "forget" its last position in the database as it restarts from the beginning of the database.
You need to help James understand why this happens. Which of the following does he need to know in order for him to fully understand what is happening in the program?
I.     When a Checkpoint is issued, all database podition is lost
II.   IMS set the position to the start of the database
III.  After a Checkpoint Call, the program needs to reposition itself
IV.  This repositioning can be done by issuing a GU Call to the last segment accessed before the Checkpoint

In response to a task you gave to James, he has written the following code to create a DBD using DBDGEN control statements. He was required to make LIBRARY the root segment while BOOKS and MAGAZINES were to be child segments to LIBRARY. But you have found out something wrong about the code. 
Look again at it and answer the question that follows.
Line1:    PRINT    NOGEN
Line2:    DBD    NAME=LIBRARY,ACCESS=HIDAM
Line3:    DATASET    DD1=LIB,DEVICE=3380
Line4:    SEGM    NAME=LIBSEG,PARENT=0,BYTES=10
Line5:    FIELD    NAME=(BOOKS,SEQ,U),BYTES=10,START=1,TYPE=C
Line6:    SEGM    NAME=BOOKSEG,PARENT=LIBSEG,BYTES=5
Line7:    FIELD    NAME=(BOOKS,SEQ,U),BYTES=10,START=1,TYPE=C
Line8:    SEGM    NAME=MAGSEG,PARENT=LIBSEG,BYTES=9
Line9:    FIELD    NAME=(MAGZINES,SEQ),BYTES=8,START=1,TYPE=C
Line10:    DBDGEN
Line11:    FINISH
Line12:    END
What is/are the corrections that James must make in order for the program to work as expected?

You can connect to an IMS Database either in DL/I or BMP mode. If you want to connect to databases in a “live” or production environment, when it is important that multiple users can access and update the data at the same time, which of the two modes would be most suitable and why?