IPv6 ACL Explicit vs Implicit Deny Any Any

Reading the IPv6 Configuration Guide (Implementing Traffic Filters and Firewalls for IPv6 Security), I came across a little known fact that seems to be very important when configuring  IPv6 access-lists on IOS.

Usually when I configured an IPv4 ACL, I explicitly defined a deny ip any any at the end, which seems like the best practice.  But what happens when you do that same thing with IPv6 ACLs.

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