The Stacks project

Definition 98.9.4. Let $S$ be a locally Noetherian scheme. Let $\mathcal{X}$ be a category fibred in groupoids over $(\mathit{Sch}/S)_{fppf}$. A formal object $\xi = (R, \xi _ n, f_ n)$ of $\mathcal{X}$ is called effective if it is in the essential image of the functor (98.9.3.1).