PreProductionAnim
PreProductionAnims are animations that are supposed to play once prior to the productionanims. Productionanims would wait until the preproduction animation was finished before playing in TS, and furthermore if it was put on a war factory, the units would wait until the animation finished before it spawned. If used on a refinery, the harvester could not un-dock until the animation finished. 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, though the harvester is not locked into the refinery while the animation finishes.