On 2013–07–10 Sanjoy Mahajan wrote:

> In certain cases, display-mathunderbraces are not quite wide enough.
> Here's a minimal example:
> 
> ===================
> \starttext
> 
> \placeformula\startformula
> \underbrace{15\,\tf cm}_{L}
> \stopformula
> 
> \stoptext
> ===================

\starttext

\placeformula\startformula
\underbrace{\unit{15 cm}}_{L}
\stopformula

\stoptext

Marco