The main central peak and two side peaks are important in the tracking mechanism. 其中心主峰值和两个副峰值对于轨道跟踪机构非常重要。
As a project grows in size and complexity, with many pieces and many people contributing to the product, it becomes necessary to have some mechanism to track its progress. 在项目内容和复杂度都在逐渐增加的情形下，这么多组件和这么多的人来构建这个产品，进度跟踪机构就成了必要的了。
