I believe you are correct.  The ils-di stuff is just kind of a framework 
starting point, not (yet) a complete end-to-end standards-constrained 
solution.

I believe you will find my thoughts and experiences on this issue 
helpful.  My own circumstances did not involve collection-level 
anything, but I still ended up using an unholy mish-hash of several 
abused metadata formats to express what I needed. 

http://bibwild.wordpress.com/2009/09/10/dlf-ils-di-dlfexpanded-service-for-horizon/

http://bibwild.wordpress.com/2009/07/31/exposing-holdings-in-dlf-ils-di-standard-format-web-service/



Owen Stephens wrote:
> I'm working with the University of Oxford to look at integrating some library services into their VLE/Learning Management System (Sakai). One of the services is something that will give availability for items on a reading list in the VLE (the Sakai 'Citation Helper'), and I'm looking at the DLF-ILS GetAvailability specification to achieve this.
>
> For physical items, the availability information I was hoping to use is expressed at the level of a physical collection. For example, if several college libraries within the University I have aggregated information that tells me the availability of the item in each of the college libraries. However, I don't have item level information. 
>
> I can see how I can use simpleavailability to say over the entire institution whether (e.g.) a book is available or not. However, I'm not clear I can express this in a more granular way (say availability on a library by library basis) except by going to item level. Also although it seems you can express multiple locations in simpleavailability, and multiple availabilitymsg, there is no way I can see to link these, so although I could list each location OK, I can't attach an availabilitymsg to a specific location (unless I only express one location). 
>
> Am I missing something, or is my interpretation correct? 
>
> Any other suggestions? 
>
> Thanks, 
>
> Owen 
>
> PS also looked at DAIA which I like, but this (as far as I can tell) only allows availabitlity to be specified at the level of items
>
>
> Owen Stephens
> Owen Stephens Consulting
> Web: http://www.ostephens.com
> Email: [log in to unmask]
> Telephone: 0121 288 6936
>
>