Re: [urn] Some initial thoughts on draft-ietf-urnbis-rfc3188bis-nbn-urn-02

Peter Saint-Andre <stpeter@stpeter.im> Thu, 09 February 2012 20:47 UTC

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Date: Thu, 09 Feb 2012 13:47:46 -0700
From: Peter Saint-Andre <stpeter@stpeter.im>
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Subject: Re: [urn] Some initial thoughts on draft-ietf-urnbis-rfc3188bis-nbn-urn-02
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<hat type='individual'/>

On 1/24/12 7:37 AM, Alfred � wrote:

> At 2012-01-24, Bengt Neiss wrote:

<snip/>

>> 2.  The sentence "Future NBN implementations SHOULD make the NBN
>> string case insensitive as well".  Is this a relevant statement?
>> Since it seems to be that the nbn_string may be case-sensitive
>> depending on syntax applied locally (ie.  already implemented) and
>> URN:s are persistent the case-sensitivity of the nbn_string must
>> always be taken into consideration...
> 
> The intent here was to refer to new usages of URN:NBNs, i.e.
> national libraries and institutions that newly establish and/or
> formalize NBNs and build national support services for URN:NBN
> for their ISO 3166 URN:NBN prefix.
> 
> So there should not be backwards compatibility issues at the URN
> level, but of course legacy NBN usage within the scope of the
> future adoptors needs to be addressed, which might lead to a
> legitimate exemption of the "SHOULD" quoted above.
> 
> Question to the list:
>   Would you prefer to drop the quoted "SHOULD" recommendation ?

Drop the "SHOULD" in favor of what?

Indeed, I find these two sentences to be in tension:

   The NBN string MAY be case
   sensitive, depending on the NBN syntax applied locally.  Future NBN
   implementations SHOULD make the NBN string case insensitive as well.

I read this as "it is OPTIONAL for existing implementations to treat the
NBN string as case-sensitive, but RECOMMENDED for new implementations to
treat the NBN string as case-insensitive".

Why the different policies for new and existing implementations? IMHO it
would be better to have the same policy for all. Since RFC 3188 did not
provide global rules ("Any national library may provide its own rules,
on the basis of its NBN syntax."), it seems better to err on the side of
caution by saying that in general NBN strings are case-sensitive, since
RFC 2141 says:

   Some namespaces may define additional lexical equivalences, such as
   case-insensitivity of the NSS (or parts thereof).  Additional lexical
   equivalences MUST be documented as part of namespace registration,
   MUST always have the effect of eliminating some of the false
   negatives obtained by the procedure above, and MUST NEVER say that
   two URNs are not equivalent if the procedure above says they are
   equivalent.

Peter

-- 
Peter Saint-Andre
https://stpeter.im/