Schematic illustration of the considered mass changes due to binary evolution. The abscissa represents time; the ordinate represents the initial stellar mass, m. ProCeps, which have an initial mass range of (m_min,Ceph, m_max,Ceph) evolve towards Cepheids (without mass exchange: violet line or with mass exchange: grey lines), the state of which is marked by the hatched area. The beginning of core helium burning is indicated by the yellow dotted line. See Sect. 3 for full explanation of the evolutionary channels and the terminology used in this paper.