“…Writing X an for the complex analytic topological space of X, the obstruction to existence of orientations for (X, ω * X ) lies in H 2 (X an ; Z 2 ), and if the obstruction vanishes, the set of orientations is a torsor for H 1 (X an ; Z 2 ). This notion of orientation, and its analogue for 'd-critical loci', are used by Ben-Bassat, Brav, Bussi, Dupont, Joyce, Meinhardt, and Szendrői in a series of papers [2][3][4][5]21]. They use orientations on (X, ω * X ) to define natural perverse sheaves, D-modules, mixed Hodge modules, and motives on X.…”