BIND 9 的query.log问题~~~

在query.log中,如下例:
queries: info: client 60.190.58.178#2370: view view_any: query: www.xxx.cn IN A +
queries: info: client 210.36.16.33#32773: view view_any: query: bbs.xxx.cn IN A -E

请问最后的IN A +和IN A - 分别是什么意思?