Level 2 corresponds to the osi layer 2 ( data link layer )
第2级对应于osi第2层(数据链路层)
Application entity title . The authoritative name of an osi application entity , usually a distinguished name from the directory .
应用实体标志，是osi应用实体的权威名称，通常是来自目录的一个与众不同的名称。
Osi school has an an excellent animation illustrating this phase : scroll to the bottom and hit play.so , why do we care ?
osi学院有一个很好的动画演示这个过程：（滚动到底点击播放）。那么，这和我们有什么关系呢？
Specifically , all free software is also open source software -- because it fits within the open source initiative ( osi ) definition of open source ( often called the osd for short ) .
European countries at that time were pursuing theopen systems interconnection ( osi ) , while the united states was using theinternet / arpanet protocol , which eventually won out .
