Zero-age main-sequence (solid lines) and the terminal-age main-sequence lines (dotted lines) above log  (L/L_⊙) > 4 of the analysed stellar models at different metallicities. The masses of some representative models (black squares) are indicated along the ZAMS. The position of the TAMS (in the model grid) where they bend towards cooler effective temperatures are marked with coloured dots, and the corresponding initial masses of these models are labelled alongside.