Where had all my apps gone?

The November update has given me the ability to not only select where to save new apps, but even more important to me is being able to move (some) apps from the the (C) drive to the (D) drive, an SD Memory Card.

I went a bit mad and moved as many apps as I could. Now, what mystified me was that I could not find them! They had not appeared anywhere in (D). Checking back in Apps and Features they are still shown as being located in (D) where they should be.

Fortunately, they are still around. When I click on their tile or in the all apps list the app launches OK. What a relief.

Eventually I did find them in (D), in an innocuious folder named WpSystem. There are sub-folders, including AppData and at last Packages. In Packages are all the transferred apps

So that is one mystery involving the new Apps and Features solved. There are others, for example what will happen when I click Modify?