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> On Wed, 2005-10-19 at 16:35, jeroen bekaert wrote:
>
>> Changing mandatory/optional occurence constraints based on METS related
>> issues is clearly an 'interoperability with other schemas' problem. Its
>> sole purpose is the trouble-free use of PREMIS in conjunction with METS
>> (only).
>
> I'm a little lost as to why this is a METS only issue.  The redundancy
> issue does not crop up in any other context?
>
> If only a few elements are mandatory, then maybe its moot.

What is worse: having a few redundant elements or having different PREMIS
implementations per (and even within a single) technological environment
(one for METS with checksum atttributes, one for METS without checksum
attributes, ..., one for IMS-CP, one for XFDU CCSDS, one for standalone
PREMIS files, and so on)?

I truly believe a single stable solution is the rights way forward.
Especially in the context of digital preservation. Just think of the
interoperability mess you create. Also, the redundancy issue is not
intrinsic to PREMIS only; METS (and yes, perhaps packaging formats other
than METS) will have the same problem with W3C XML Signature, ISO/IEC
MPEG-7 MDS, etc.

>> It should be clear that mandatory/optional contraints on PREMIS
>> elements/attributes should be dictated by the abstract PREMIS data
>> dictionary only.
>
> That does make sense to me, but it was suggested at the top of this
> thread that the definition of "mandatory" in the context of the data
> dictionary is not the same as the definition of "mandatory" in XML
> Schema.

well, imo, it must be the same. see above: 1 problem 1 solution. I ll
forward Ryan's email.

jeroen