# Centering a tag on an align environment

I want to create a list of two items, labeled (1) and (2), with a $\star$ tagged to the left, and centered vertically in between the (1) and (2). If I use the following:

\begin{align*}\tag{$\star$}
(1)&stuff here\\
(2)&more stuff here
\end{align*}


Then the star is immediately to the left of the (1). How can I move that star down a bit, so as to seem like the whole list is labeled star, as opposed to just item (1).

I'm open to using enumerate/aligned/equation environments as well if that would be better. Thanks!

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Make the inner construction inside an array, which boxes it into a single entry:

\documentclass{article}
\usepackage[leqno]{amsmath}
\begin{document}

\begin{align*}
\tag{$\star$}
(1) & \text{stuff here} \\
(2) & \text{more stuff here}
\end{array}
\end{align*}

\end{document}


• \quad is the space between the entries;
• c l is the column specification for the left (numbered) and right (textual) columns;
• \arraystretch greater than 1 gives a little air between the array rows.

Caveat: array's interior is not set in \displaystyle, so you may have to force this explicitly if your construction contains something that is set differently under that style.

You would obtain a similar output if you'd used aligned (and there's also alignedat for multiple alignment points):

\tag{\star} \begin{aligned} (1) &\quad \text{stuff here} \\ (2) &\quad \text{more stuff here} \end{aligned}

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I'd prefer alignedat probably. Surely not array (it doesn't use \displaystyle). –  egreg May 17 at 20:07
@egreg: Thanks. Forgot about that. I've added it as a caveat. –  Werner May 17 at 20:18
Wonderful. Thank you! –  Jared May 17 at 21:22

Here's an alternative, using tabstackengine. The gap between the items is defined by \setstacktabulargap{length}, and the inter-row skip is defined by \setstackgap{L}{length}. In this case, I \rlaped the star, so that it did not affect the centering. I found the \hfil approach easier in this case, because \centering redefines \\, which concomitantly requires an alternative stacking end-of-line character to be used.

\documentclass{article}
\usepackage{tabstackengine}
\setstacktabulargap{2\tabcolsep}
\setstackgap{L}{1.2\baselineskip}
\begin{document}
\noindent\rlap{($\star$)}
\hfil
\tabularCenterstack{cl}{
(1)& stuff here\\
(2)& more stuff here
}\hfil
\end{document}


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