#3 added content part 7.1 Enter Update Exit
#3 added content part 7.1 Enter Update Exit, more comments
#3 comments added for part 7
#3 added content part 7.2 Enter Update Exit
#3 better comments part 7.2
#3 added content part 7.3 Enter Update Exit
#3 added content 7.4
#3 update labels on part 7