Definition 39.18.2. Let $S$ be a scheme. Let $(U, R, s, t, c)$ be a groupoid scheme over $S$. Let $g : U' \to U$ be a morphism of schemes. The morphism of groupoids $(U', R', s', t', c') \to (U, R, s, t, c)$ constructed in Lemma 39.18.1 is called the restriction of $(U, R, s, t, c)$ to $U'$. We sometime use the notation $R' = R|_{U'}$ in this case.

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