关于结构体的理解

有一段代码不是很理解 期望高手不吝赐教

typedef struct ALR_STRUCT {
    unsigned short usErrorMonitoringEnable;
    unsigned short usErrorConditionEnable;
    unsigned short usOccurred;
    unsigned short ausCondition[MAX_NUM_ALARM];
    long           ausDelayTime[MAX_NUM_ALARM];
    unsigned short ausIsActive[MAX_NUM_ALARM];
    unsigned short ausToSendCome[MAX_NUM_ALARM];
    unsigned short ausToSendGone[MAX_NUM_ALARM];
    unsigned short ausDelayRunCome[MAX_NUM_ALARM];
    unsigned short ausDelayRunGone[MAX_NUM_ALARM];
    long           ausDelayEndCome[MAX_NUM_ALARM];
    long           ausDelayEndGone[MAX_NUM_ALARM];
    unsigned short ausWasSentCome[MAX_NUM_ALARM];
    unsigned short ausWasSentGone[MAX_NUM_ALARM];
} ALR_STRUCT;

typedef struct ALARM_STRUCT {
    unsigned short usAlarmAcknowledgeFlag;
    ALR_STRUCT     rFault;
} ALARM_STRUCT;
static ALARM_STRUCT     rAlr = {0};
上面是相关的申明部分， 然后rAlr.rFault.ausIsActive[CMN_FAULT_VACC_REQUEST_DATA_INCONSISTEND] 这个是什么意思呢 这里CMN_FAULT_VACC_REQUEST_DATA_INCONSISTEND 是一个常数 比如30 这样。 还有上面的申明也不是很明白 谢谢解答哈