来龙去脉（來龍去脈）　

◎ 来龙去脉 láilóng-qùmài

[pedigree;origin and course of development;cause and effect; ins and outs; sequence of actions; ways and wherefores; whence and wither] 原是过去风水先生的说法,认为山势如龙,从头到尾都有血脉连贯。现在常用来比喻事物的来历或事情的前因后果

文件的来龙去脉