Furthermore Hot Gas Injection can be used in 2 ways (maybe more).
1 injected after the expansion device so as too reduce the liquid content in the evap by a small amount of volume displacement and a lot by dumping loads of energy into the evap.

2 injected after the evap. so as to condition the suction vapour without such an impact on the evap.

sorry If this is a little vague but I would have to read up on this to get into the nitty gritty.

Whats the slide valve then and all this d ,dd ,j & k
sounds more like cup sizes to me?