Testing hypothesis 5 with f_pms = 1.0. Survey of η,δ parameter space for solutions of the K type with f_pms = 1 (Eq. (4)) for the canonical pre-main-sequence data, together with the Lupus and UScA pre-main-sequence data sets. Open circles and small dots delineate models consistent with the data at the 1 and 5 per cent confidence level, respectively. The K1 IPF is shown as the thick cross, and the straight line is as in Fig. 3. The thick solid dots show models consistent at the 50 per cent level or better.