Loopback interface terminology issue

[Brian E Carpenter <[e-mail]>]

Hi,

This come rather late in the day, but it results from some wordsmithing
difficulties in a draft in another WG:

The IPv6 specs are very clear that an address is assigned to an interface,
not to a node, but they don't say anywhere that non-loopback addresses may
be assigned to the loopback interface. However, sometimes as a practical
matter, it's necessary to assign a routeable address (GUA or ULA) that
is not created via a specific IPv6 interface. Conventionally, that is
done by assigning it to the loopback interface.

However, the only place I have found that defines 'loopback interface' for
IPv6 is in the addressing architecture: 'a virtual interface (typically
called the "loopback interface") to an imaginary link that goes nowhere.'
(RFC 4291, section 2.5.3). The text only mentions the loopback address ::1.

Do people agree with something like the following?

'Note that other forms of unicast IPv6 address may be assigned to the
loopback interface, in cases where an address is assigned to the node
without being assigned to the interface to a specific link.'

This is after all common practice in various operating systems; we
just never documented it, as far as I know.

Regards
   Brian Carpenter