# Column dimension tabu

Instead have two columns of the same dimension I want that the first one smaller while the other one that depends on the content. I'm just writing a table there in the first column I put the name of some equations (for each row) and in the other column the equation. I tried with

\begin{tabu} { | X[l]{0.1/textwith} | X[c] |}
\hline
item 11 & item 12 \\
\hline
item 21  & item 22   \\
\hline
\end{tabu}


but give me the error

Package array error: illegal pream-token

How can I do it?

The input {0.1/textwith} is illegal. In general, if you want to specify a fraction of the text width, the syntax would be 0.1\textwidth. Anyhow, that's out of place in that context.

I also added a final \strut because tabu doesn't. I'd stay at arm's length from the package.

\documentclass{article}
\usepackage{tabu}

\begin{document}

\begin{tabu} { | X[0.1,l]<{\unskip\strut} | X[c] |}
\hline
item 11 & item 12 \\
\hline
item 21  & item 22   \\
\hline
\end{tabu}

\end{document}


The fraction of \linewidth should be specified in the optional argument to X.