Extending work of Meinhardt and Partsch, we prove that two varieties are isomorphic away from a subset of a given dimension if and only if certain quotients of their categories of coherent sheaves are equivalent. This result interpolates between Gabriel's reconstruction theorem and the fact that two varieties are birational if and only if they have the same function field. Contents 1. Quotient categories 909 2. A locally ringed space 913 3. Gabriel's theorem 917 4. The group of autoequivalences 919 Acknowledgments 921 References 921It is a well-known fact that two varieties (i.e., irreducible and reduced schemes of finite-type over a field k) X and Y are birational if and only if their function fields are isomorphic. At the same time, a theorem of Gabriel says that X and Y are isomorphic if and only if their categories of coherent sheaves are equivalent (as k-linear categories). In this article we show that these results are actually related: they are the two extreme cases of our main theorem.Before giving a precise statement, we introduce some notation. For an integer k, we write Coh ≤k (X) ⊂ Coh(X) for the subcategory of sheaves supported in dimension at most k. There is a robust theory of quotients of abelian categories, and we define C k (X) ∶= Coh(X)/ Coh ≤k−1 (X). It is often convenient to re-index these categories by codimension, defining C c (X) ∶= C dim X−c (X). We have C dim X (X) = Coh(X), and one shows that C 0 (X) is equivalent to finite-dimensional vector spaces over the function field of X. Finally, recall that two schemes X and Y of finite-type over a field are isomorphic in codimension c (resp., outside of dimension k − 1) if there exist open subsets U ⊂ X, V ⊂ Y such that U is isomorphic to V , and the codimensions of X ∖ U and Y ∖ V are at least c + 1 (resp., dimension at most k − 1). In particular, two varieties X and Y are birational if and only if they are isomorphic in codimension zero.