Subject: Re: [dispatch] draft-montemurro-gsma-imei-urn-17 and draft-allen-dispatch-imei-urn-as-instanceid-11

From: [email-masked] (Dale R. Worley)
Date: Fri, 8 Nov 2013 21:07:35 -0500 (EST)

> From: Andrew Allen <[email-masked]>

> Main question on the ABNF is whether the ABNF should be extensible
> to support additional NSS under the GSMA NID.  The concern seems to
> be that new NSS might be created without going through the IETF
> consensus process. The draft states that this process will be used
> for approval of any additional NSS.  My concern is if we remove
> extensibility from the ANF now does that create problems for parsers
> if new NSS are defined and approved in the future?

I think the question is whether any parser conforming to the current
version might be required to handle an extended form without rejecting
it.

For instance, if an entity is required to strictly validate a URN,
then it doesn't matter if the parser is able to handle future
extensions, because the validator would reject them anyway (as the
validator wasn't built to know how to validate the extended form).

On the other hand, any extended form would still be a syntactically
correct URN, so any entity that was handling them as generic URNs
would have no difficulty with extensions.

The problematic case is an entity which needs to handle "any IMEI
URN", but isn't expected to understand them in detail.

But on the whole, I favor providing some sort of generic syntax, so
the designers of entities are warned that their systems may need to
handle future extensions, and are warned of the syntactic extent of
those possible extensions.

Dale