The dasha used specifically for the judgement of longevity and for the timing of danger: the Jaimini sign dasha read with the houses of death and the maraka planets, in the questions where ayurdaya is the subject.
Meaning
Shoola means spear, and the system is the tradition's instrument for the question of death: the signs take periods, and the periods of the signs connected with the 8th, the marakas and the lagna are read for the danger to life. It is a specialised dasha, not a general one, and BPHS lists it among the systems it names.