This is just a dolphin directory structure void of all the files. I use this for storing a copy of any Dolphin source files I modify. It's quite useful when you have a number of altered source files on your server, and need to apply an upgrade patch. I unzip an upgrade patch, then use Beyond Compare to show file differences between the upgrade patch, and my repository of change files in this directory structure. If any of the files in my directory structure will be overwritten by uploading the Dolphin upgrade patch to the server, Beyond Compare makes it easy to transfer the file customizations to the corresponding files in the upgrade patch. Then, when the upgrade patch is uploaded to the server, the custom edits will be in place.
You must of course, be diligent about storing to this directory structure, a copy of any source files you change.