PreProductionAnim
PreProductionAnims are animations that are supposed to play once prior to the productionanims. In RA2, preproductionanims are entirely unused and most of their functionality has been lost.
A test on conyards, airpads, barracks, war factories, repair depots, and refineries shows that the only known function of PreProductionAnim in RA2 is that it fires an animation every time a harvester docks with the refinery, without the function of locking the harvester into the refinery until the animation stops, unlike ProductionAnim.