On Feb 27, 2006, at 3:12 PM, Pete Johnston wrote:

> Madeleine Rothberg wrote:
>
>> You are correct that all the information on what access modes are 
>> present and adapted can be conveyed simply, in the case where each 
>> resource has only one access mode. But many resources have more than 
>> one access mode. If foo.avi is a video with two access modes 
>> (auditory and visual) and bar.txt is a text-based adaptation of 
>> foo.avi, I can't tell if it is a text adaptation of the audio 
>> (captions) or a text adaptation of the visual (description of 
>> important imagery in the video). It is for this reason that a4a needs 
>> to include some way of indicating which mode in the original resource 
>> is adapted by a particular adaptation.
>> In order to meet the needs of specific users who have no access to a 
>> particular access mode, we need to know which access modes are 
>> present in a resource and which ones have been adapted, and in what 
>> ways.
>
> Ah, OK, thanks.
>
> Yes, I can see that means my simplistic model doesn't work, and 
> something like the "role" property (or Andy's suggestion of multiple 
> "one-per-mode" subproperties) is needed.
>
> Does this also implies that for a single adapted resource, there is 
> only one mode, and only one mode in the original which is adapted?
>
> If not - i.e. if it is possible that the adapted resource has multiple 
> access modes, each of which may apply to distinct access modes in the 
> original - then, given that the DC model is essentially one of binary 
> relationships, I think that would require a re-think.

I'm not a DC expert, or even a DC user, so I can't say what the right 
solutions will be for DC. But yes, a single resource can have multiple 
access modes adapting distinct access modes in an original. For 
example, if you have videoA which has audio and visuals, and then 
videoB, which is the same video with captions and audio descriptions 
added, then videoB adapts videoA for two different sets of users -- 
those who need alternatives to audio and those who need alternatives to 
visuals. But perhaps (as was alluded to in Pete's post on "The Real 
Problem") there can be more than one metadata record and it is up to 
the system to find them and compare each one to the needs of the user 
in question, to see if there are useful alternatives available.

-Madeleine