Answer to the delta transform. Delta transforms are just another transform on top of your normal transform. This is useful in several situations. The most common is if you use empties for animation. Once you have the empty position where you want it you apply the transform to the delta so that later when you clear transforms(alt+g, alt+s, and alt+r) the empty will go back to the delta transform position. Basically the same thing as the rest pose with an Armature. Another use is if you have a driver on a transform channel and want to adjust or offset that value you can do it thru the delta.
