ZZ _ Ring -- integers or zero element

n_R promotes the integer n to the ring R.
1_R provides the unit element of the ring R.
0_R provides the zero element of the ring R.
0_M provides the zero element of the module M.

The return value is either a ring element, or a vector.

i1 : R = QQ[a..d];

i2 : 1_R o2 = 1 o2 : R

i3 : 100_(ZZ/101) o3 = -1 ZZ o3 : --- 101

i4 : 0_(ZZ^3) o4 = 0 3 o4 : ZZ