I am not sure if I was as clear as I could be, so I have slightly revised my original post. 

We have set up our digital library to browse by collection but are also hoping that we will be able to limit a search to a particular collection.  In other words, search for “equipment” but just in one of the collections.  We would also like to be able to search across all the collections.  In other words, search for “equipment” across all collections.  Is this possible?   Mary