I have a table of numbers that are aligned using the 'S' format of siunitx (so they are aligned by the decimal point). I need to mark the statistically significant numbers somehow, and using bold font or asterisks to mark these don't make them stand out very well. I am not allowed to use colour in the table, so I was thinking of trying underlining. However, if I use \underline{}, the underlined numbers are no longer aligned by the decimal point and are left aligned instead.
Is there any way I can underline items whilst keeping them aligned by the decimal point?
Here is a basic version of the code for the table I have so far:
\documentclass{article}
\usepackage{etoolbox,siunitx,booktabs,threeparttable,multirow,array,graphicx}
\robustify\bfseries
\robustify\tnote
\begin{document}
\sisetup{detect-weight=true,detect-inline-weight=math,table-align-text-post=false}
\begin{table}
\caption{Insert caption here}
\centering
\begin{threeparttable}[b]
\begin{tabular}{SS}
\toprule
{Column 1} & {Column 2}\\
\midrule
7.1 & 4.2\\
\underline{8.7} & 6.5\\
9.3 & \underline{1.0}\\
\bottomrule
\end{tabular}
\end{threeparttable}
\end{table}
\end{document}
Not sure how to post an image of what the output looks like.
I did have a search online for anyone asking a similar question, but couldn't find anything.

\ulinething withulem, but I hadn't done the\robustifybit. I will try that now to see if it works. – emmalgale Feb 10 '14 at 17:16\robustify\ulineand it all works perfectly! So frustrating when you miss little things like that, so very grateful for this website!! – emmalgale Feb 10 '14 at 17:19\sisetup, I have addedtable-format=2.1to reduce the space each number was taking up. When I do this, the underline values don't align with the non-underlined ones. Is there any way I can fix this without removing thetable-format? – emmalgale Feb 17 '14 at 17:35\ulineapproach does not work then. Thanks. – LaRiFaRi Aug 05 '15 at 09:59\uline{8.77} & 6.5\\and the decimal alignment (which, I guess, is what was wanted by theS-column) vanishes. – LaRiFaRi Aug 05 '15 at 14:13S[table-format = 1.2]as a column specifier. Nothing to do with\uline. – karlkoeller Aug 05 '15 at 14:19\uline{9.3}then as well, it will get distorted again. If you leaveSSand don't use\ulineat all, the decimal point alignment works even withouttable-format=1.2or alike. That is why I think your solution is having some mistake. The follow up of the OP goes in similar direction, of course. – LaRiFaRi Aug 05 '15 at 14:21