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 =================== Using 2013.05.28 00:36 MKIV (from vanilla TL2013), the left brace tip starts under the vertical bar of the "1", instead of enclosing the serif as well. The right brace tip ends between the last two tines of the "m", instead of enclosing the whole "m" and its serifs. With 2013.04.09 10:38 MKII, the brace tips extend just slightly beyond the "15 cm", which is better. However, they seem slightly too close. As a test, I ran the comparable plain-TeX file through LuaTeX and PDFTeX. ================== $$ \underbrace{15\,\rm cm}_{L} $$ \bye ================== The gap between the right brace tip and the text is slightly greater (with either LuaTeX or PDFTeX), and it looks right. (With the 2012.05.30 MKIV on live.contextgarden.net, the result is similar to the Lua/PDFTeX versions, though not identical, and also looks reasonable.) -Sanjoy