[Moims-dai] Telecon Notes?

D or C Sawyer Sawyer at acm.org
Sun Jul 22 13:27:54 UTC 2018 

Dear all,

I would like to return to this point in the discussion on David’s proposal as I think David has made some valuable points that may get lost.  I have not heard anyone disagree that, under some circumstances, a physical book does not need RepInfo.  As an example, I believe an Archive implemented primarily for the preservation of physical books (Content Data Objects) understandable to the associated Designated Community would be fully justified in not conjuring up information, to be called RepInfo, just to meet someone’s concept of a best practice or a mandatory requirement for some type of certification.  There may, or may not, eventually be a requirement for the addition of real RepInfo to such CDOs.  This is all about practical implementations.  

In contrast, the OAIS RM is a conceptual model and its AIP is the key unit of information that is being preserved.  The AIP is defined to include RepInfo with the CDO, forming Content Information, as this Content Information entity is of central importance to the preservation of digital information.  I see no reason to alter this Content Information definition and I don’t believe anyone is proposing to do so. At the same time I have no problem recognizing that some implementations, such as that given in the Archive example above, may have an AIP whose Content Information is the CDO alone. This simply reflects local, practical, reality. The example highlights the possible differences between a concept and local reality.  In my opinion, when there is good justification, such differences should not be of major concern. David’s proposal for the OAIS RM regarding implicit and explicit RepInfo is designed to acknowledge this reality.  While I had some objection to the ‘implicit’ part of his proposed wordingl, I firmly support the attempt and believe some appropriate words can be found. It should not take a lot of discussion to find such words if there is agreement on the objective.

When the OAIS RM uses the phrase ‘Representation Information’, it should mean the same concept everywhere in the document.  It should not also stand for some made up sentence just to satisfy a conceptual information category.  Therefore I think John’s second paragraph below is properly understood as an implementation view where he thinks an actual AIP should always have a RepInfo category.  One could consider this a possible best practice, but personally I would not go that far.  Discussion of this particular view  makes sense in the context of ISO 16363.  As for the OAIS RM, again I support David’s attempt to clarify that some AIP implementations may not need explicit RepInfo as it has been defined in the OAIS RM.   

Cheers-
Don


> On Jul 17, 2018, at 4:11 AM, John Garrett <garrett at his.com> wrote:
> 
> Hi,
>  
> I’m also uncomfortable with the updated conformance.  I also feel that it would be a significant change and I think it would open up a door to keep expanding the conformance requirements.  I would prefer to try to update Section 2 a bit and keep the Conformance section the same.
>  
> Also I’m not on board with having original data objects in an AIP that do not require RepInfo.  I think if we have a physical book in local language, we should still require RepInfo as we form the AIP.
>  
> Peace and joy,
> -JOhn
>  
>   <>
> From: MOIMS-DAI [mailto:moims-dai-bounces at mailman.ccsds.org] On Behalf Of D or C Sawyer
> Sent: Monday, July 16, 2018 11:36 PM
> To: MOIMS DAI List <moims-dai at mailman.ccsds.org>
> Subject: Re: [Moims-dai] Telecon Notes?
>  
> Dear All,
>  
> The proposal for section 1.4 (conformance) is to include section 4.2 information modeling for conformance. This is a considerable increase in requirement which originally we did not feel comfortable requiring.  This is not backward compatible so it may be controversial in the larger community.
>  
> The proposal for section 4.2.1.3 states that an explicit or implicit lack of Representation Information can be regarded as a sufficient expression of meeting a Representation Information requirement. There is a bit of a problem with ‘implicit’ as it could be used as justification for no Representation Information when in fact it was needed.  Perhaps the ‘implicit’ should be dropped?
>  
> However this kind of statement on Representation Information is also true for selected components of PDI (which can also be recursive), depending on the judgement of the Archive in support of the associated Designated Community. I believe some appropriate text is needed for PDI as well, particularly if 4.2 is now to be part of conformance.
>  
> Once again I will be unable to participate in the Tuesday DAI telecon as I’ll be working with my contractor.
>  
> Cheers-
> Don
>  
> 
> 
>> On Jul 16, 2018, at 8:00 AM, David Giaretta <david at giaretta.org <mailto:david at giaretta.org>> wrote:
>>  
>> I have added a suggested change  - see http://review.oais.info/show_bug.cgi?id=236 <http://review.oais.info/show_bug.cgi?id=236>
>>  
>> Also, in the resolution of http://review.oais.info/show_bug.cgi?id=35 <http://review.oais.info/show_bug.cgi?id=35> there was an action in comment 4 to create a related suggested change which I have done in http://review.oais.info/show_bug.cgi?id=237 <http://review.oais.info/show_bug.cgi?id=237>
>>  
>> ..David
>>  
>> From: MOIMS-DAI <moims-dai-bounces at mailman.ccsds.org <mailto:moims-dai-bounces at mailman.ccsds.org>> On Behalf Of David Giaretta
>> Sent: 15 July 2018 19:24
>> To: 'MOIMS-Data Archive Interoperability' <moims-dai at mailman.ccsds.org <mailto:moims-dai at mailman.ccsds.org>>
>> Subject: Re: [Moims-dai] Telecon Notes?
>>  
>> Hi Don and others in MOIMS-DAI
>>  
>> It looks as if we can reach a conclusion – see below for some general suggestions. I will try to suggest something specific on the review site.
>>  
>> Regards
>>  
>> ..David
>>  
>> -----Original Message-----
>> From: MOIMS-DAI <moims-dai-bounces at mailman.ccsds.org <mailto:moims-dai-bounces at mailman.ccsds.org>> On Behalf Of D or C Sawyer
>> Sent: 13 July 2018 14:18
>> To: MOIMS DAI List <moims-dai at mailman.ccsds.org <mailto:moims-dai at mailman.ccsds.org>>
>> Subject: Re: [Moims-dai] Telecon Notes?
>>  
>> Hi David, et al.,
>>  
>> I mostly agree with your comments, but see below.
>>  
>> > On Jul 9, 2018, at 7:12 AM, David Giaretta <david at giaretta.org <mailto:david at giaretta.org>> wrote:
>> > 
>> > Hi all
>> > 
>> > I missed the call on which these notes report, but I must make a few comments which I am sure I would have made in the meeting.
>> > 
>> > In summary Don's arguments about the Information Model seem to derive from examples of some specific Data Objects, without explicit consideration of the Designated Community, which I argue is misleading, and can be addressed by adding text to the standard to address such "edge cases", as discussed next.
>>  
>> During the subject telecon it was mentioned that a CDO with no needed Representation Information depended on the Designated Community. The point of the discussion was to note that this is a real example. It could be thought of as an ‘edge case’, as you say, or perhaps the modeling and text should be improved to bring it into compliance.
>>  
>> Yes we definitely should add text to explain this, perhaps in the discussion in section 4.2.1.3 Representation Information.
>>  
>> > 
>> > The argument about whether or not a Data Object needs Representation Information in order to be understood is misleading in that, as I responded in a previous email, it depends on the Designated Community. In other words, if the Data Object is a piece of paper written in English, and members of the Designated Community can read and understand English then there is no need for an explicit English dictionary because the Designated Community's Knowledge Base includes that. 
>> > 
>> > However, if the Designated Community were to be defined as readers of Chinese then Representation Information such as an English Dictionary would be needed. So, if one claims that this piece of paper does not need Representation Information then that is in the context of a Repository's definition of a specific Designated Community. 
>> > 
>> > So in general modelling terms the OAIS Information Model is right - a Data Object needs Representation Information in order to be used/understood. However there may be some specific instances where, for a specific Designated Community, explicit Representation Information is not needed.
>> > 
>> > In modelling terms, I would regard cases such as English written on paper to be read by English readers as an "edge case" and to be consistent in such edge cases one should say that the Representation Information is the statement that "for the specific Designated Community no additional explicit Representation Information is currently needed". As far as I can see this would make the model complete and consistent. We could add some wording to the discussion of Representation Information and Designated Community to make this clear.
>> > 
>> > In terms of the idea of OAIS being only a "communications framework" - yes it is that, especially the Functional Model, but it also provides something more, namely guidance of what one needs in order to preserve digitally encoded information, and OAIS lays these out in terms of conformance. Thus, the repository needs an AIP with all its components; it needs to undertake all the Mandatory Responsibilities. 
>>  
>> Yes on the Mandatory Responsibilities, but on the ‘AIP with all its components’ there is considerable ambiguity.  The information modeling conformance only addressed the Information Object and the Information Package as given in Section 2.2. The Information Package is broken into SIPs, AIPs, and DIPs,  It is clear that SIPs and DIPs may not contain all the Representation Information or PDI.  The implication (not stated) is that the AIP does contain all the Representation Information and PDI.  Certainly it does conceptually.  However the conformance section (1.4) addresses an actual Archive.  The example above raises the conformance issue for an Archive that only preserves hardcopy documents, with no Representation Information, yet still fully understandable to its Designated Community, Maybe it also finds it doesn’t need all the PDI.  Can it still claim to be OAIS conformant? I would say ‘yes’ as long as it is making a reasonable argument for not having all the components of the section 2.2 information models.  Note also that none of the modeling in section 4.2 is required for OAIS RM conformance.  Given that OAIS RM conformance has sometime been a topic of concern to others as well as to this working group, I recommend it be clarified.
>>  
>> I agree – we should make it clear that 2.2 and 4.2 are both included in the Mandatory Responsibilities and also in the Conformance section. In section 2.2 we say “While formal modeling of information is provided in section 4, some key concepts are provided in this subsection” but this should be expanded also.
>>  
>> > 
>> > I realise that to some readers all this may seem like a very abstruse, uninteresting discussion. However, it IS important because there will be times when repository staff will come across puzzling cases and we need to make sure, as far as humanly possible, that OAIS provides useful, correct and consistent guidance when read carefully.
>>  
>> Yes, we should want the OAIS RM to be as clear and unambiguous as we can make it.
>>  
>> Yes I think we have relied on some implicit connections that should be made explicit.
>>  
>> Cheers-
>> Don
>>  
>>  
>> > 
>> > Hope that helps
>> > 
>> > ..David
>> > 
>> > 
>> > 
>> > -----Original Message-----
>> > From: MOIMS-DAI <moims-dai-bounces at mailman.ccsds.org <mailto:moims-dai-bounces at mailman.ccsds.org>> On Behalf Of John Garrett
>> > Sent: 07 July 2018 05:55
>> > To: 'MOIMS-Data Archive Interoperability' <moims-dai at mailman.ccsds.org <mailto:moims-dai at mailman.ccsds.org>>
>> > Subject: [Moims-dai] FW: Telecon Notes?
>> > 
>> > 
>> > 
>> > -----Original Message-----
>> > From: Don Sawyer [mailto:topcottageguys at gmail.com <mailto:topcottageguys at gmail.com>] On Behalf Of D or C Sawyer
>> > Sent: Monday, July 2, 2018 8:18 AM
>> > To: John Garrett <garrett at his.com <mailto:garrett at his.com>>
>> > Cc: Hughes, John S (398B) <John.S.Hughes at jpl.nasa.gov <mailto:John.S.Hughes at jpl.nasa.gov>>; Mark Conrad <Mark.Conrad at nara.gov <mailto:Mark.Conrad at nara.gov>>
>> > Subject: Re: Telecon Notes?
>> > 
>> > Hi John,
>> > 
>> > I’ve made a few comments to your comments.  I think our differing views are pretty clear.  If you want to add some more comments, or not, I have no objections to your sending this out to the wider group.
>> > 
>> > Cheers-
>> > Don
>> > 
>> > 
>> > _______________________________________________
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