[44.006]关于SABM 一处疑问

风情123

请教下:44.006中:
"8.4.1.4 Contention resolution establishment procedure"中
If an SABM command with an information field is received when the "establishment  in process" flag has been set,the data link layer entity in the BS shall compare the store information field with the information field received in the SABM command. If they are not identical, the SABM command shall be ignored without any notification. If they are identical, the data link layer entity shall respond, at the earliest possible opportunity, with a UA response with:

主要比较迷惑的是发送SABM command中带有信息域的,说是进行与"the data link layer entity in the BS "进行比较,不是很懂"the data link layer entity in the BS "里面都有什么的??按理说未发SABM command时对端应该没有"SABM command"中信息域的任何信息,怎么可以比较呢??