Table too wide in iopart class

Question

I'm preparing my first manuscript for journal submission with the iopart document class. Since it's for a publication, there are typesetting constraints imposed on me (that I'm not always aware of). I'd like to include a table in the paper, but it's too wide for the manuscript for the time being. I include the table like

\begin{table}
\caption{\label{tab:table} Caption.}
\begin{indented}
\footnotesize
\item[]\begin{tabular}{@{}lllllll}
\br
Heading 1 & Heading 2 & Heading 3 & Heading 4 & Heading 5 & Heading 6 & Heading 7 \\
\mr
1.1 & 1.2 & 1.3 & 1.4 & 1.5 & 1.6 & 1.7 \\
2.1 & 2.2 & 2.3 & 2.4 & 2.5 & 2.6 & 2.7 \\
\br
\end{tabular}
\end{indented}
\end{table}

One way to slightly narrow the table that I've seen people do is to split longer headings over two lines. How do I do that? Has anyone else written an article for an IOP journal with a wide table and can share what other tricks they used to fit it to the page within the journals's guidelines?

Answer 1

Point (ii) on page 20 of the user guide of the iopart document class says the following about tables and the indented environment:

The normal style is for tables to be indented. This is accomplished by using \begin{indented} . . . \end{indented} and putting \item[] before the start of the tabular environment. Omit these commands for any tables which will not fit on the page when indented. [emphasis added]

Since the indented wrapper is preventing the tabular material from fitting inside the text block, you actually have official permission to get rid of the indented wrapper.

\documentclass[12pt]{iopart}
\usepackage{showframe} % <-- draw framelines around text block
                       % (omit from real document)

\begin{document}
\begin{table}

\caption{Caption.}\label{tab:table} 
\footnotesize
\centering % <-- new

\begin{tabular}{@{} lllllll @{}}
\br
Heading 1 & Heading 2 & Heading 3 & Heading 4 & 
Heading 5 & Heading 6 & Heading 7 \\
\mr
1.1 & 1.2 & 1.3 & 1.4 & 1.5 & 1.6 & 1.7 \\
2.1 & 2.2 & 2.3 & 2.4 & 2.5 & 2.6 & 2.7 \\
\br
\end{tabular}

\end{table}
\end{document}