If I want to keyframe a simple location change then I just set a key frame by moving the object to its initial location, press I, select location keyframe, move the timeline cursor to when the change ends, move object to next position, make another keyframe as before. The animation runs as expected.
If I do the same using delta keyframes FROM THE I DROP DOWN, I was expecting the object to move the same as above relative to whatever starting position I put the object in. But the object doesn't move. In the Properties, Object tab the delta transform numbers remain at zero. The object stays at the end of the cycle.
I know how to duplicate the object and type in numbers into the Object tab Delta transforms to produce the same movement but offset. I also know how to convert [all of the] keyframes to delta keyframes. I just do not understand what the purpose of delta keyframes in the I menu are for and how they work.