On 30 Nov 2021, at 19:34, Alexandre Christe via ntg-context wrote:

Dear list,

What I've done is to play with mathalignment and \framed. Here is a MWE:

\starttext \defineoverlay[midrule][{\blackrule[height=.02cm,width=5.5cm]}]

\framed[frame=off,background=midrule,boffset=.65cm]{\startformula \startmathalignment[n=12,align={middle,middle,middle,middle,middle,middle,middle,middle,middle,middle,middle,middle}] \NC \NC S_6 \NC= \NC 1 \NC+ \NC 2 \NC+ \NC\dots \NC+ \NC 5 \NC+ \NC 6 \NR \NC + \NC S_6 \NC= \NC 6 \NC+ \NC 5 \NC+ \NC\dots \NC+ \NC 2\NC+ \NC 1 \NR \NC\NC 2S_6 \NC= \NC 7 \NC+ \NC 7 \NC+ \NC\dots \NC+ \NC 7 \NC+ \NC 7 \NR \stopmathalignment \stopformula} \stoptext

Is there a simpler way to typeset something like this?

How about: \usecolors[svg] \starttext \ssa\bold \starttabulate[|r|CT{red}c|c|CT{yellow}c|c|CT{green}c|c|CT{cyan}c|c|CT{blue}c|c|CT{darkmagenta}c|] \NC S = \NC 1 \NC + \NC 2 \NC + \NC 3 \NC + \NC 4 \NC + \NC 5 \NC + \NC 6 \NC\NR \NC + S = \NC 6 \NC + \NC 5 \NC + \NC 4 \NC + \NC 3 \NC + \NC 2 \NC + \NC 1 \NC\NR \HL[cornflowerblue] \NC 2S = \NC 7 \NC + \NC 7 \NC + \NC 7 \NC + \NC 7 \NC + \NC 7 \NC + \NC 7 \NC\NR \stoptabulate \stoptext — Bruce Horrocks Hampshire, UK