It enables you to freeze (or hold) a scene, at a particular point in the process of creating a scene, usually an important point.

And if you are not happy with what you do after holding a scene, you can simple fetch the held scene.

Basically Hold & Fetch just saves and loads a scene, but with one major advantage, only a single mouse click, no navigating of directories or typing of filenames.

Before I created Hold & Fetch I used to end up with lots of 'temp1.scn', 'temp2.scn', 'temp3.scn' etc. files when creating a new scene.

Now when you reach a tricky point in a scene simply left-click the Hold & Fetch icon on the eXtensions panel, to hold the scene, and to fetch it back simply right-click the Hold & Fetch icon (No dialog boxes, just a single mouse click).