L1 as a function of several quantities used to parameterize HB morphology. Total length of the HB from Fusi Pecci et al. (1993, lower-left panel), logarithm of the maximum temperature along the HB from Recio-Blanco et al. (2006, lower-middle panel), median HB color (Δ( V −  I)) from Dotter et al. (2010; lower-right panel), HBR ratio (upper-left panel), and maximum and median mass loss from Gratton et al. (2010; upper-middle and upper-right panel).