I see. The problem is that we really have two levels of "type" here: the general kind ("entity", "assocation") and for entities the "table name".

documentType might be an alternative in the CouchDB terminology but it doesn't solve the issue of these two levels. I also considered to collapse them into one property with values such as "A" (for an assocation) and "E:BlogPost" (for an entity BlogPost) to further reduce the document store. Such single field could be named documentType then.