Lemma 89.16.3. Let $\mathcal{F}$ be a category cofibered in groupoids over $\mathcal C_\Lambda$. Then $\mathcal{F}$ satisfies (RS) if the condition in Definition 89.16.1 is assumed to hold only when $A_2 \to A$ is a small extension.

Proof. Apply Lemma 89.3.3. The proof is similar to that of Lemma 89.8.2. $\square$

In your comment you can use Markdown and LaTeX style mathematics (enclose it like $\pi$). A preview option is available if you wish to see how it works out (just click on the eye in the toolbar).