Hi list! I'm curious about vertical typesetting in ConTeXt. As far as I know, LuaTeX supports four text directions, but LTL is broken for Manchu script (letters are displayed unjoined in LTL mode) and LuaMetaTeX does not support vertical directions anymore, at least as primitives.

I found the following solution:

https://tex.stackexchange.com/a/140972/193767
I reproduce the code (in XeLaTeX), just in case
% !TEX TS-program = xelatex
\documentclass{scrartcl}
\usepackage{fontspec}
\newfontfamily{\dcw}[]{DaicingWhite}%
\begin{document}
\noindent
Line above\\% to demonstrate that the lines are being stacked as normal
\rotatebox{-90}{%
\XeTeXupwardsmode1\\% successive lines will be stacked upwards instead of downwards
\begin{minipage}{4em}% this will be the vertical length of the Mongolian section
{\dcw% Font: Daicing White
1 ᠮᠠᠨᠵᡠ ᡤᡳᠰᡠᠨ\\% direct Unicode input of Manchu letters
2 ᠮᠠᠨᠵᡠ ᡤᡳᠰᡠᠨ
}% End font
\end{minipage}
\XeTeXupwardsmode0
}% End rotatebox

\noindent
Line underneath
\end{document}

and I see XeTeX uses the primitive \XeTeXupwardsmode and some other tricks to get the proper display of Manchu text, so maybe MKII can do the magic using XeTeX as an engine. How would one use ConTeXt MKIV for this task? Is it possible to emulate \XeTeXupwardsmode in ConTeXt as a first step? Thank you very much.

Jairo :D