As part of the 22FEB2016 update the support for site specific url shares is now available.

It has always been possible to have the same url on many documents i.e. /app - but when rendering a website it would always find the first document in the space associated with the site.  

Now during rendering it checks to see if there is a document linked to the site that has the matching share URL and shows it - if not, it falls back to the existing mechanism of space level match.

This is particularly handy in url based app production - so you can now have a "lab" version of the page and also one that is in production.

eg

http//mydomain-lab.1blankspace.com/app

http//mydomain.1blankspace.com/app

will now render differently, but the controllers that are linked to the "app" context can be the same and transported without change between "lab" and "prod".