> While reviewing the work Hoa Nguyen has been doing on 
> XX-8646, I realized that there is a restriction on resource 
> lists that we hadn't taken proper account of:  In a single 
> resource list, all the URIs have to be different.  See RFC 
> 4662 section 4.6 for the official prohibition -- but the 
> restriction must be obeyed because in a "partial state" 
> update, the only way the subscriber can tell which resources 
> have been updated is by recognizing their URIs.
> 
> I haven't checked, but I suspect that sipXconfig does not 
> enforce this restriction -- a user can enter one extension 
> multiple times in his BLF list.  (Doing that wouldn't make 
> sense with a desk telephone with a handful of BLFs, but on a 
> receptionist's console with 60 BLFs, one might want to have a 
> single extension displayed more than once (e.g., appearing in 
> several different groups).)
> 
> An alternative strategy would be to have sipXconfig detect 
> duplicate entries in a resource list and modify them so as to 
> make them unique, but functionally identical.  Doing this 
> would allow users to enter one URI/extension into his BLF 
> list more than once.
> 
> In order to make "different" versions of a URI, I think the 
> best (only?) way is to add a URI parameter whose only purpose 
> is to make the URIs different.  E.g., under the rules of RFC 
> 3261 section 19.1.4, the following are different:
> 
> sip:[email protected];unique=1
> sip:[email protected];unique=2
> sip:[email protected];unique=3
> 
> (Although they all compare "the same" with 
> sip:[email protected], so the latter can't be used in the set.)
> 
> (Note re sipXrls:  When mapping a ResourceReference to a 
> ResourceCached, remember to remove this special 
> URI-parameter, so all these URIs cache as one URI.)
> 
> So we need to enhance how sipXconfig handles BLF lists.  The 
> user-visible question is whether we allow duplicate URIs in a 
> BLF list.
> 
> Comments?

Can you think of a use case where it would be required to allow someone to 
enter a BLF twice because I cannot come up with one?  If nobody can find a 
reason why it makes sense to allow duplciated BLF then, knowing that it muddies 
the water for partial updates, it seems to me we should disallow it in config.

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