Doug Ewell wrote: > TUS 3.0 states (p. 24): "In contrast to the bidirectional > case, the choice to lay out text either vertically or > horizontally is treated as a formatting style. > [...] why should overrides of default horizontal > directionality be a plain-text issue but overrides of > default vertical directionality be a higher-level > "formatting style" issue?
Because all vertical scripts (CJK and Mongolian) can also be written horizontally, whereas modern right-to-left script cannot be written left-to-right. Also, all horizontal scripts, when embedded in Far East text, may be written vertically by rotating them 90� degrees (clockwise for LTR scripts, counterclockwise RTL scripts). So you can happily define a system-level vertical/horizontal preference, and use it blindly for plain text in any kind of script. _ Marco
