Can come in characters ‘\mathchardef\coprod="1360 \mathchardef\bigvee="1357 \mathchardef\bigwedge="1356 \mathchardef\biguplus="1355 \mathchardef\bigcap="1354 \mathchardef\bigcup="1353 \mathchardef\intop="1352 \def\int{\intop\nolimits} \mathchardef\prod="1351 \mathchardef\sum="1350 \mathchardef\bigotimes="134E \mathchardef\bigoplus="134C \mathchardef\bigodot="134A \mathchardef\ointop="1348 \def\oint{\ointop\nolimits} \mathchardef\bigsqcup="1346 \mathchardef\smallint="1273’ or as functions \mathop{\rm log},....
In plain.tex, the \limits and \nolimits are used only after \mathop. Without the following we get a complain from ‘$\arctan (2)$’ about \nolimits not following the operator immediately in ‘fonts’ mode. This is so because the definition ‘\arctan ->\mathop {\rm arctan}\nolimits ’ gets output of code from \rm.
<..html math and non-math symbols???..>
\def\:temp{\nopic:gobble\o:nolimits:}
\HLet\nolimits=\:temp
\def\:temp{\nopic:gobble\o:limits:}
\HLet\limits=\:temp
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