Regarding the description of RT, which items are correct? (Multiple selection)Multiple selection

A、Each VPN instance is associated with one or more pairs of VPN Target attributes, which are used to control the release and reception of VPN routing information between sites.
B、The settings of Export Target and Import Target are independent of each other, and multiple values ​​can be set to achieve flexible VPN access control (reference answer)
C、RT can be divided into two types of VPN Target attributes: Export Target and Import Target (reference answer)
D、The RT value is published to neighbors through Update messages in the form of BGP extended community attributes (refer to the answer)