To acknowledge a SubscribeEventgroup entry, the SubscribeEventgroupAck entry shall be used and shall be used with the values as in the SubscribeEventgroup entry it answers. 要确认SubscribeEventgroup entry，应使用SubscribeEventgroupAck entry，并应与其回复的SubscribeEventgroup entry中的值一致。
Service ID, Instance ID, Major Version, Eventgroup ID, TTL, Counter, and Reserved shall be the same value as in the Subscribe that is being answered. 服务ID，实例ID，主要版本，事件组ID，TTL，计数器和保留位应与正在应答的Subscribe中的值相同。
A SubscribeEventgroupAck entry shall set the TTL field to the value of the SubscribeEventgroup entry, it acknowledges. SubscribeEventgroupAck entry应将TTL字段设置为它确认的SubscribeEventgroup entry的值。
SubscribeEventgroupAck entries referencing events and notification events that are transported via multicast shall reference an IPv4 Multicast Option and/or and IPv6 Multicast Option. The Multicast Options state to which Multicast address and port the events and notification events will be sent to. 针对通过multicast传输的events和notification events的SubscribeEventgroupAck entry应引用IPv4 Multicast Option和/或IPv6 Multicast Option 。Multicast Option表明notification event将会发送到哪个Multicast地址和port口。
