The WN spectral sequence was expanded to include WN2–WN9, and the definitions refined based on the relative strengths of the NIII lines at 463.4–464.1 nm and 531.4 nm, the NIV lines at 347.9–348.4 nm and 405.8 nm, and the NV lines at 460.3 nm, 461.9 nm, and 493.3–494.4 nm. These lines are well separated from areas of strong and variable He emission and the line strengths are well correlated with temperature. Stars with spectra intermediate between WN and Ofpe have been classified as WN10 and WN11 although this nomenclature is not universally accepted.