Illustration of our classification scheme. Shown is the number of BNS systems for each sequence of stellar types of the primary (rows) and of the secondary (columns) at Z = Z_⊙ = 0.014. The combination of primary and secondary evolutionary sequences creates 46 evolutionary sequences, but 95% of the systems are found in 12 of them. The sequences of numbers on the y axis and on the x axis are the series of stellar types (see Table 1) for the primary and the secondary, respectively. Only systems with Δt_delay < t_Hubble are shown.