The illustration shows a code segment with the lines numbered from 1 through 20 and the annotations are as follows:

"//Header file dtime.h: This is the interface for the class DigitalTime.
 //Values of this type are times of day. The values are input and output in
 //24-hour notation, as in 9:30 for 9:30 AM and 14:45 for 2:45 PM.
 #ifndef DTIME_H
 #define DTIME_H
#include <iostream>
using namespace std;"
"namespace dtimesavitch" annotated as "One grouping for the namespace dtimesavitch. Another grouping for the namespace dtimesavitch is in the implementation file dtime.cpp."
 "{
 class DigitalTime
 {
<The definition of the class DigitalTime is the same as in Display 12.1.>
 };
 }//end dtimesavitch
#endif //DTIME_H"