Definition 4.35.2. Let $\mathcal{C}$ be a category. Suppose that $F : \mathcal{C}^{opp} \to \textit{Cat}$ is a functor to the $2$-category of categories. We will write $p_ F : \mathcal{S}_ F \to \mathcal{C}$ for the fibred category constructed in Example 4.35.1. A split fibred category is a fibred category isomorphic (!) over $\mathcal{C}$ to one of these categories $\mathcal{S}_ F$.

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