The doctrine describes the past cause only in terms of avijja and sankhara but in point of fact avijja is invariably followed by tanha and upadana and sankhara too always lead to kammabhava. So Patisambhidamagga comments on the doctrine as follows.
“Avijja is ignorance that dominates us while doing a kammic deed. Sankhara means collection and exertion of effort. Tanha is the craving for the results of an action in the present life and hereafter. Upadana is obsession with action and its result. Kammabhava is volition. These five factors in the past constitute the cause of present rebirth.”
Thus, we have to consider all these five links viz., avijja, tanha, upadana, sankhara and kammabhava if we are to describe the past cause fully. Of these, avijja, tanha and upadana are labelled kilesavatta (cycle or round of defilements). Sankhara and kammabhava are called kammavatta (cycle of actions). The commentary makes a distinction between sankhara and kammabhava, describing the prior effort, planning, etc., preparatory to an act as sankhara and the volition at the moment of doing the act as kammabhava. Thus, seeking money, buying things, etc., prior to an act of dana comprise sankhara while the state of consciousness at the time of offering is kammabhava. Preliminary activities leading to an act of murder are sankhara while cetana or volition at the time of killing is kammabhava.