We have an outstanding work item to address the question of whether/how
to capture the fact that a collection includes some items of a specified
media-type or physical medium (e.g. that a digital collection includes
some TIFF images or PDF documents; or a physical collection includes oil
paintings or ink drawings etc.), so that applications can support
searching or grouping of descriptions based on this information. 

There was a fairly lengthy debate around this point on the list last
year (see [1], [2] and follow-on messages), and a straw-poll, results at
[3] with more discussion.

I think there were broadly five opinions expressed:

(i) we don't need to express this at all in the DC CD AP;

(ii) we should express this information, and we should capture this
information using the dc:format property in a statement about the
collection;

(iii) we should express this information, and we should define a new
property (e.g. cld:itemFormat) to use in a statement about the
collection, and that property should _not_ be a subproperty of dc:format

(iv) we should express this information, and we should define a new
property (e.g. cld:itemFormat) to use in a statement about the
collection; and that property _should_ be a subproperty of dc:format

(v) whether we want the information or not, we can't capture this
information in a statement about the collection (because any attempt
would break DCMI's "one-to-one" rule)

I don't think there was any clear consensus for the way forward, though
I think at one point we were close to having a small majority of those
who voiced an opinion preferring (iii):

I've drawn up a proposal for a property based on approach (iii) with
some examples:

http://dublincore.org/collectionwiki/PropertyitemFormat

And an outline description of its use in the DC CD AP

http://dublincore.org/collectionwiki/DCCDAPitemFormat

I've set up a survey on the Jiscmail website to canvass opinions on this
proposal. An announcement to the list from the Jiscmail server should
follow shortly. The survey will be available for two weeks.

Please complete the survey - it is very short. Feel free to post
comments here as well, but please do complete the survey so that your
vote is counted!

Cheers
Pete

[1]
http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0312&L=dc-collections&P
=60
[2]
http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0504&L=dc-collections&P
=451
[3]
http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0507&L=dc-collections&P
=56