Multiplicative group scheme (${\mathbb{G}}_{m,A}=\mathrm{Spec}A[t,t^{-1}]$)

The multiplicative group scheme represents units: its $R$-points are $R^{\times }$. Multiplication is specified by $t\mapsto t\otimes t$ on the coordinate ring. It is the principal open subset $D(t)$ of the affine line and the one-dimensional split algebraic torus.

// Target: ringed-space.bigb