These commands are called menu titles and each corresponds to an NX functional category. 每个菜单标题下面都对应着相应的命令。
A user points and clicks on a menu bar and its immediately subordinate list of options appears in a small window just below it. 用户指向并单击其中的一个菜单标题，即可弹出直接属于此标题的选项列表窗口。
