Could someone kindly provide a skeleton ifcfg-eth0:[X] for creating an alias with a IPv6 address and no IPv4 address?

Or, alternatively, what's the IPv6 equivalent of this:

in /etc/sysconfig/network-scripts/ifcfg-eth0:1

DEVICE=eth0:1
ONBOOT=yes
BOOTPROTO=static
IPADDR=42.69.66.66
NETMASK=255.255.255.0

Or does this not even make sense in IPv6 space?

I know that I can use, for example:

IPV6INIT=yes
IPV6ADDR=2600:4200::6900:6666:dead:beef

But then do I need to specify that there is no IPv4 address associated with this alias? If so, how? And do I need to also specify the IPV6_DEFAULTGW? Or can it piggyback on the eth0 (unaliased) gateway, which is specifed, like with IPv4 aliases?

EDIT:

Answered my own question!

The easiest way to accomplish this seems to be not to create an alias as with IPV4, but to specify, for example, IPV6ADDR_SECONDARIES=2600:4200::6900:6666:dead:beef on the script for the base interface, e.g. ifcfg-eth0.