ABAP--关于abap的subroutines的几个注意点

1、参数引用传递(Parameters Passed by Reference)
使用USING或CHANGING不带value关键字来声明参数引用传递。代码样例：
FORM subr USING    p1 [{TYPE type}|{LIKE field}]
                   p2 [{TYPE type}|{LIKE field}]
                   ...
          CHANGING p1 [{TYPE type}|{LIKE field}]
                   p2 [{TYPE type}|{LIKE field}]
              &