how the first basic instructions { INC, DEC, JZ } can create three more instructions--unconditional jump J, CLR, CPY. In a sense CPY used both CLR and J plus the base set. If register #3 had had contents initially, the sum of contents of #2 and #3 would have ended up in #3. So to be fully accurate CPY program should have preceded its moves with CLR (1) and CLR (3).

However, we do see that ADD would have been possible, easily. And in fact the following is summary of how the primitive recursive functions