![](https://secure.gravatar.com/avatar/b9093698dc66621c584549528e50e2d1.jpg?s=120&d=mm&r=g)
\starttext
\m{\root3\of2}
\stoptext
works.
But
\starttext
\startMPcode
label("\m{\root3\of2}", origin);
\stopMPcode
\stoptext
doesn't.
Running `LuaMetaTeX' on `trial' with
``/home/fvleung/ConTeXt/tex/texmf-linux-64/bin/mtxrun --autogenerate
--script context trial.tex''
resolvers | formats | executing runner 'run luametatex format':
/home/fvleung/ConTeXt/tex/texmf-linux-64/bin/luametatex --jobname="trial"
--fmt=/home/fvleung/ConTeXt/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luametatex/cont-en.fmt
--lua=/home/fvleung/ConTeXt/tex/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/luametatex/cont-en.lui
cont-yes.mkiv --c:currentrun=1 --c:fulljobname="./trial.tex"
--c:input="./trial.tex" --c:kindofrun=1 --c:maxnofruns=9
--c:texmfbinpath="/home/fvleung/ConTeXt/tex/texmf-linux-64/bin"
open source > level 1, order 1, name 'cont-yes.mkiv'
fonts > beware: no fonts are loaded yet, using 'lm mono' in box
system >
system > ConTeXt ver: 2021.07.27 19:27 LMTX fmt: 2021.7.28 int:
english/english
system >
system > 'cont-new.mkxl' loaded
open source > level 2, order 2, name
'/home/fvleung/ConTeXt/tex/texmf-context/tex/context/base/mkxl/cont-new.mkxl'
system > beware: some patches loaded from cont-new.mkiv
close source > level 2, order 2, name
'/home/fvleung/ConTeXt/tex/texmf-context/tex/context/base/mkxl/cont-new.mkxl'
system > files > jobname './trial', input './trial.tex', result
'./trial'
fonts > latin modern fonts are not preloaded
languages > language 'en' is active
open source > level 2, order 3, name './trial.tex'
fonts > preloading latin modern fonts (second stage)
fonts > 'fallback modern-designsize rm 12pt' is loaded
metapost > initializing instance 'metafun:1' using format 'metafun'
and method 'default'
metapost > loading 'metafun' as 'metafun.mpxl' using method 'default'
metapost > initializing number mode 'scaled'
metapost > trace > This is MPLIB for LuaMetaTeX, version 3.11,
running in scaled mode.
metapost > trace >
metapost > trace > loading metafun for lmtx, including the plain
1.004 base definitions
metapost > trace >
tex error > tex error on line 7 in file ./trial.tex: Argument of
\root has an extra }
32\normalstopimath \fi
<inserted text>
\par
<to be read again>
}
<lua output> }
<local> \global \setbox \mptextbox \hbox {\clf_mptexttoks
}
<inserted text>
[[special cmd: end local call]]
<to be read again>
\relax
...