horizontal-in-vertical text setting
A typographic feature in Japanese vertical writing where a short run of horizontal characters (often two digits or a few Latin letters) is set within a single vertical column, keeping the characters upright rather than rotated.
In vertical writing, setting digits side by side as in '10月' is tate-chū-yoko.
This typesetting software makes it easy to configure horizontal-in-vertical text.
Compound of 縦 (tate, 'vertical'), 中 (chū, 'inside'), and 横 (yoko, 'horizontal'), literally 'horizontal inside vertical'. The term describes the typographic practice directly.