\documentclass{aa}

\usepackage{booktabs}
\usepackage{graphicx}
\usepackage{txfonts}
\usepackage{hyperref}

$if(texpackages)$
$for(texpackages)$
\usepackage
$if(opts)$
[
$for(opts)$
$opts$,
$endfor$
]
$endif$
{$texpackages.name$}
$endfor$
$endif$

$if(preambleinput)$
$for(preambleinput)$
\input{$preambleinput$}
$endfor$
$endif$

\begin{document}

\title{$title$}

\author{
$for(author)$
$author.name$,
$if(author.affiliation)$
$for(author.affiliation)$
\inst{1}
$endfor$
$endif$
\and
$endfor$
}
\institute{
$for(author)$
$if(author.affiliation)$
$for(author.affiliation)$
$author.affiliation$\\
$endfor$
\and
$endif$
$endfor$
}


\date{
Received
$if(received)$
$received$
$else$
YYY
$endif$
/ 
Accepted 
$if(accepted)$
$accepted$
$else$
XXX
$endif$
}

$if(abstract.context)$
\abstract
{$abstract.context$}
{$abstract.aim$}
{$abstract.methods$}
{$abstract.results$}
{$abstract.conclusions$}
$else$
\abstract{$abstract$}
$endif$

$if(keywords)$
\keywords{
$for(keywords)$
    $keywords$ -- 
$endfor$
}
$endif$

\maketitle

$body$

$if(bibliography)$
$for(bibliography)$
\bibliography{$bibliography$}
$endfor$
$endif$

\end{document}