6.3.e Describe IPv6 network address translation

6.3.e [ii] NPTv6

NPTv6 is simply rewriting IPv6 prefixes. If your current IPv6 prefix is 2001: db8: cafe::/ 48 then using NPTv6 it would allow you to change it to 2001: db8: fea7::/ 48 – that is it. It is a one for one prefix rewrite – you can’t overload it, have mismatching prefix allocations sizes, re-write ports or anything else . Importantly, it doesn’t touch anything other than the prefix. Your network/ host portion remains intact with no changes.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 6032-6034).  . Kindle Edition.

http://blogs.cisco.com/enterprise/why-would-anyone-need-an-ipv6-to-ipv6-network-prefix-translator/