说明：  本书所要介绍的就是Cadence 公司所出品的Allegro Layout 软件工具，书中每 个章节的出现顺序系按照实际的电路板设计流程而编排，而每一个章节又按照下 列的方式编排，以期让使用者可以较快地进入使用状况
(This book is to be introduced by Cadence s production company Allegro Layout software tools, the emergence of each section of the book the order in accordance with the actual circuit board design process and schedule, and each section is arranged according to the following manner, with a view to allow users to can quickly access the status)