Источник:
http://www.agermark.com/2017/07/new-...-creating.html
==============
The "July 2017" release has a new model called "Retail" and elements have been moved from other models to this model.
Even if you have made your own solutions exclusively with extensions, this might break your build because you might now need to add a reference to the "Retail" model.
But when you add that, you can't build your solution on the "1611" release anymore because build will complain about not knowing the "Retail" model listed in the Descriptor file.
So, even if your code works perfectly on both "1611" and "July 2017", you could have a need to branch out in VSTS to have two different Descriptor files.
Источник:
http://www.agermark.com/2017/07/new-...-creating.html