Recent developments in the emission spectrum of RR Tel include the emergence of C IV, [A IV], [K IV], [Fe IV], [Fe V]. A special search for the hitherto unknown [Fe IV] lines proved successful in the light of Edlén's independent predictions from laboratory data. Fe II lines have faded steadily relative to [Fe II]. The rate of development towards higher stages of ionization is compared with that of other slow novae. Time intervals between corresponding stages of RR Pic, RR Tel, RT Ser and η Car are found to be approximately in the ratios 1:6:17:220. One result of this comparison is to give some grounds for supposing that η Car brightened from a pre-nova state not very long before Halley's observation in 1677.