log ([O iii] 5007 Å/Hβ) vs. log ([N ii] 6584 Å/Hα) diagram for the individual-star zero-age solar metallicity simulations. The results are compared with the grid by Dopita et al. (2006) where dotted lines join points of equal ages, and filled lines join points with equal metallicity. Left: grid with logarithm of the ratio of the cluster mass to the ambient presure, ℛ, equals to  −2, simulations with fixed M_clus = 100 M_⊙ are plotted as large filled symbols (and models with fixed Q(H⁰) with small open ones). Right: grid with ℛ = 2, simulations with fixed log Q(H⁰) = 49.87 are plotted as large open symbols (and models with fixed M_clus with filled open ones).