Upper box: schematic pole-on view of the Be star (blue dot), its decretion disc and spiral extensions (sky blue), the WD companion, and its truncated accretion disc (magenta). The dark blue contour shows the Roche lobe of the system. The boxes at the bottom provide zooms on vertical cuts through the inner part of the Be decretion disc (left) and the surroundings of the WD (shown by the violet dot) with its magnetically truncated accretion disc (right). The red crosses correspond to the emitting regions of the primary X-rays. The left box illustrates the case of the magnetic star-disc interaction with magnetic field lines that connect the star and the disc. The right box corresponds to an accreting magnetic WD scenario where a magnetically channelled flow connects the truncated accretion disc to the magnetic poles of the WD.