List, With recent betas, since a fix for tagged elements in tables, underbar processing seems to have changed (or perhaps I just noticed it after that fix). Previously, the following highlight definition worked for both pdf and export outputs: \definehighlight [Term][style={{\underbar}}] With the current betas (2018-10-02 and 2018-10-03) this no longer works for all output formats. I have tried a few variants, and the results are as follows: Using [style={{\underbar}}], the pdf output now shows no underlining, while the html export has the expected underlining. Using [style={\underbar}] or [style=\underbar] or [style=underbar], the pdf output shows the expected underlining, while the html export may show continuous underlining after the first use, and in any case eventually loses all formatting. In a large enough document, an error is generated in the html, but not in the log as far as I can tell: <div class="error">...eXt/tex/texmf-context/tex/context/base/mkiv/lxml-tab.lua:1192:  backtrack stack overflow (current limit is 1000)</div> A test harness: xxx.css: highlight[detail="Term"], div.highlight.Term {     display         : inline ;     font-style      : inherit ;     font-variant    : inherit ;     font-weight     : inherit ;     font-family     : inherit ;     color           : inherit ;     text-decoration : underline ; } xxx.tex: \setupbackend[export=yes] \setupexport[cssfile=xxx.css] \definehighlight[Term][style=underbar]%       pdf ok, html bad %\definehighlight[Term][style={{\underbar}}]% pdf bad, html ok \starttext \dorecurse{200}{%   \startparagraph     \samplefile{ward}     \Term{pollakis legomenon}     \samplefile{bryson}   \stopparagraph} \stoptext The html output of the above shows the text as a single long line and when displayed the last paragraph are run together with no formatting. For a larger recurse (250 does it for me) the error described above is triggered. As a work-around, I can enable one variant or the other based on the output mode, but clearly there is an issue here. -- Rik