Hello and my apologies for a question that has surely been asked and 
answered. I searched the archive but couldn't find my answer, so here is my 
question:

My librarian would like to create a finding aid for her entire library, and 
this would include content found in other finding aids. A meta-finding aid, 
if you will. I am just the computer programmer, but it's been left up to me 
to encode everything and format the xml, so I am bumbling through as best as 
I can.

She'd like to make the container type = 'shelf'

I'm unable to find documentation that this is a valid attribute. It isn't 
disallowed though. What are your thoughts?

Thanks!