Weil divisor

《Solitons: Differential equations, symmetries, and infinite-dimensional algebras》 · 第 309 页 · Definition 11.36

For an integer $k\ge0$ we denote by $X^k$ the set of closed integral subschemes of codimension $k$. The free abelian group over $X^k$ is denoted by $Z^k(X)$. An element of $Z^1(X)$ is called a Weil divisor.