Documentation lacks information about HA setups and IPv6

[junicast]

In a case where CARP is used and IPv6 should the Interface be set to the CARP IP in:

Services / DHCPv6 Server & RA / LAN / Router Advertisements / RA Interface

By default the interface name is selected in the dropdown menu. Second option is the CARP IP in the dropdown which would make more sense to me.
The documentation has explicit information about IPv4 but there is no information about IPv6 at all.