J-line
In the study of the arithmetic of elliptic curves, the j-line over any ring R is the coarse moduli scheme attached to the moduli problem Γ]:
with the j-invariant normalized a la Tate: j = 0 has complex multiplication by Z, and j = 1728 by Z.
The j-line can be seen as giving a coordinatization of the classical modular curve of level 1, X0, which is isomorphic to the complex projective line.
