Lemma 38.12.6. Let $f : X \to S$ be locally of finite presentation. Let $x \in X$ with image $s \in S$. If $f$ is flat at $x$ over $S$, then there exists a commutative diagram of pointed schemes
\[ \xymatrix{ (X, x) \ar[d] & (X', x') \ar[l]^ g \ar[d] \\ (S, s) & (S', s') \ar[l] } \]
whose horizontal arrows are elementary étale neighbourhoods such that $X'$, $S'$ are affine and such that $\Gamma (X', \mathcal{O}_{X'})$ is a projective $\Gamma (S', \mathcal{O}_{S'})$-module.
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