[jerf]

"If you have suggestions for language that make that distinction more clearly than the document currently does, I'm happy to incorporate it. :)"

Currently where it says "an IP loopback addresses", it may be worth saying something like "any of the IP loopback addresses for the device".

I agree that technically "an IP loopback address" ought to be sufficient, but I have also found it is a very common belief, probably even the majority belief, among people who use networking that "127.0.0.1" is the one and only loopback address. (I've lost count of the systems I've slightly broken just by feeding them 127.1.1.1 or equivalent.) I'm sure people who are the sort to read and write standards know better, but since it doesn't hurt the standard itself to emphasize the point, perhaps it's worth it.

[SysArchitect]

Thankfully IPv6 defined a single "localhost" or loopback IP: ::1/128

There is none of this 127/8 mess.

[the8472]

that "mess" is great for testing though, you can spin up numerous instances each on their own loopback address.

[TimWolla]

You can use a link local address of your public interface in IPv6.

[the8472]

That's just one, adding more require elevated privileges, with 127.0.0.0/8 you have 256³ at your disposal.