书上的CODE如下
DATA boats;
INFILE 'c:\MyRawData\Boats.dat';
INPUT Name $ 1-12 Port $ 14-20 Locomotion $ 22-26 Type $ 28-30
Price 32-36;
RUN;
PROC TABULATE DATA = boats;
CLASS Locomotion Type;
VAR Price;
TABLE Locomotion ALL, MEAN*Price*(Type ALL);
TITLE 'Mean Price by Locomotion and Type';
RUN;


标红的为疑问部分，麻烦大神们解答一下这三句代码的含义吧！！！