Corbet diagram for the observed distribution of the 64 binary radio pulsars with a He WD companion. The plot reveals four regions, labelled by I, II, III, and IV, that may be understood from an evolutionary point of view (see text). The pulsars in region II are also marked by a circle in the PṖ–diagram in Fig. 19 and their potential link to an AIC origin is discussed in the text (figure updated after Tauris 2011).