A locally-unique host is a FQDN defined by you and resolved only by you; similar to how a [hosts file](https://en.wikipedia.org/wiki/Hosts_(file)) is implemented. Not to be confused with @canonically-unique-host.
You have the option to share your interpretation of how the host is resolved (e.g.,
localhost always resolves to
127.0.0.1) but the resolution is not canonically enforced (e.g., someone else can map
localhost to any arbitrary IP address).
Hosts in a public subscription can be considered @canonically-unique-host's within the @I2P network but, ultimately, you are free to re-define them as you wish.
Haven primarily uses @canonically-unique-host resolution while @I2P only uses @locally-unique-host resolution.
@I2P's and @Kovri's assigned top-level domain is currently
.i2p and @Kovri intends to only process/use the
.i2p top-level domain