service box line
/ˈsɜːvɪs ˈbɒks ˈlaɪn/
n
English · service box line中文 · 发球区线Español · línea de cuadro de servicioFrançais · ligne de boîte de service
意味：Line drawn 46 cm from the sidewall that marks the service box at both ends of the service zone.