The Stacks project

Definition 10.78.1. Let $R$ be a ring and $M$ an $R$-module.

1. We say that $M$ is locally free if we can cover $\mathop{\mathrm{Spec}}(R)$ by standard opens $D(f_ i)$, $i \in I$ such that $M_{f_ i}$ is a free $R_{f_ i}$-module for all $i \in I$.

2. We say that $M$ is finite locally free if we can choose the covering such that each $M_{f_ i}$ is finite free.

3. We say that $M$ is finite locally free of rank $r$ if we can choose the covering such that each $M_{f_ i}$ is isomorphic to $R_{f_ i}^{\oplus r}$.