Strength of the Balmer H|$\delta$| absorption line as a function of strength of the 4000 Å break for red-sequence galaxies. For individual galaxies, only red-sequence galaxies with z-band magnitude brighter than 21.5 are investigated, while all of the red-sequence galaxies are used for the composite spectra. We apply the definitions by Worthey and Ottaviani (1997) and Balogh et al. (1999) to measure the equivalent width of H|$\delta$| and |$D_n4000$|⁠, respectively. Symbols and colors of the individual galaxies are different depending on their position and redshift (figure 5 and table 2). The open symbols show the measurement for the individual galaxies, and the filled symbols show the measurement for the composite spectra of red-sequence galaxies (figure 8). The solid lines are model tracks of the stellar population synthesis of Bruzual and Charlot (2003) with different star formation histories: simple stellar population (red), e-folding time of |$0.1\:$|Gyr (pink), |$0.3\:$|Gyr (green), and |$1.0\:$|Gyr (yellow green) in exponentially declining star formation history, and constant star formation (blue). Stellar ages of 0.1, 0.5, 1, 2, 3, 5, and |$10\:$|Gyr are shown by red filled dots for SSP. The dotted and dashed lines show model tracks of SSP with |$0.4\, Z_{\odot }$| and |$2.5\, Z_{\odot }$|⁠, respectively, where the stellar age of |$2\:$|Gyr is marked by the plus symbol. The gray-scale histogram shows the distribution of the SDSS galaxies at |$z= 0.04$|–0.1 with the contours of |$30\%$|⁠, |$68\%$|⁠, and |$90\%$| of the galaxies enclosed. (Color online)