一博客中，一段的注释的解释：[From: ]

/**  * Access to the system diagnostic event record.  System diagnostic events are  * used to record certain system-level events (such as garbage collection,  * activity manager state, system watchdogs, and other low level activity),  * which may be automatically collected and analyzed during system development.  *  * 
This is not the main "logcat" debugging log ({
    @link android.util.Log})!  * These diagnostic events are for system integrators, not application authors.  *  * 
Events use integer tag codes corresponding to /system/etc/event-log-tags.  * They carry a payload of one or more int, long, or String values.  The  * event-log-tags file defines the payload contents for each type code.  */

 

在Google Andorid代码中：

system/core/include/cutils/event_tag_map.h 第24行

 

其中另一博客亦有详细的介绍：[From: ]

 

总而言之，按个人理解，这个是用来设定、配置输出日志(event log)格式的。