On Montblanc nibs the “D” usually stands for Durchschreibfeder, a manifold nib: an exceptionally hard, barely yielding nib for writing carbon copies. On some examples of the 32, though, that reading does not square with the evidence. The nib so marked writes comparatively flexibly, and the breather hole sits appreciably further from the tip than it does on true manifold nibs, where it moves up close to the point. The shape of the tip, too, departs from the familiar picture on the 32, where a pointed cut-out leaves the 585 hallmark visible.
Despite these discrepancies, collectors regard such pens as having left the factory in this form; several examples are known in collections and have been judged original by experienced collectors. Precisely what the “D” denotes in this context has never been settled. A later modification or nib change need not therefore be assumed, though in an individual case it cannot be ruled out entirely.