This invention is involving the creation of a sub-sequence net (hereafter briefly as Sub SN). The Sub SN is a kind of sequence net encapsulation that includes sub-routine structure of N+1 single machines. Based on the fact that the sequence net call instruction of sequence net call function in the environment of sequence net computers of this invention is a single machine instruction which can call the operation of a Sub SN comprising N+1 branch programs. In N+1 branch programs, the sequence net call instruction calls Sub SN devices and realizes the call of sequence net. In this invention, grade call and sequence call of sequence net are created to meet requirements of random events and ordered events of models.