Notice in line 3 that, if there are attributes to an element, they should be informed right after the element's name, followed by the element content (line 4).
注意第3行中，如果元素存在某些属性，就应该恰好在元素名称之后，元素内容(第4行)之前告知。
3
Tree structure view: in this format, the WBS is depicted using a tree structure with each child element connected to the parent element through a line.