Stale Reference Manipulation is a glitch that allows you to overwrite nearly anything stored on the Actor Heap with the position and angle data of an unloaded actor that is currently attached to a loaded actor.
Please note that MM3D's heap works in a vastly different way from OoT, MM, and OoT3D, among other things because the heap contains everything that loads dynamically, not actors. It also doesn't clear up on scene change, only on reset or on "dawn of the Nth day" telops. This adds new possibilities for heap manip that aren't possible in other games, but so increases the difficulty of finding them considerably. Discussion about how this was almost way harder to find until we found the technique to make a gap in the heap of size 320/330 and force the bombchu allocation to "round up" to eat that space, thanks to the massive headers of S.Moriya
As of this moment, SRM can be used for Human during the 1st Cycle of the game and for Wrong Warping to the moon (commonly known as "Moonwarp".)