Thank you for your prompt reply, Mikael.
I like this new way of defining math functions.

Mikael Sundqvist <mickep@gmail.com> 於 2024年2月28日 週三 下午2:46寫道:
Hi,

\definemathfunction [lcd]

You can also add
[mathlimits=yes]
[mathlimits=no]
[mathlimits=auto]

if you want the limits to go always below, never below or below in
display, respectively.

/Mikael

On Wed, Feb 28, 2024 at 1:26 AM fv leung <fvleung@gmail.com> wrote:
>
>
> \starttext
> % copy from wiki
> \definemathcommand[lcd][nolop]{\mfunction{lcd}}
>
> With \contextversion, the math command \tex{lcd} gives \m{\lcd} (nothing)!
>
> \stoptext
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maillist : ntg-context@ntg.nl / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
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