beg_offset-到设备的起始偏移量，对于目录是0。
Beg_offset - Starting offset into device, 0 for directory.
youdao
每个栏位起始的字元位置由该目录规定。
The character position of the start of each field is specified by a directory.
应用推荐
模块上移
模块下移
不移动