! Missing # inserted in alignment preamble

Question

I have a problem in compiling my tex file using nle.cls document class. The problem seems to be with package pgfplotstable. If I comment it our every thing works fine. The package disrupts the working of maketitle. Here is the warning that I get:

! Missing # inserted in alignment preamble.
<to be read again> 
                   \cr 
l.65 \maketitle

? 

Here is the minimal working example.

\documentclass{nle}

\usepackage{pgfplotstable} 


\title[Natural Language Engineering]
      {Natural Language Engineering \LaTeX\ Supplement}
\author[\LaTeX\ Supplement]
       {C\ls A\ls M\ls B\ls R\ls I\ls D\ls G\ls E\ns
        \TeX\ls -\ls T\ls O\ls -\ls T\ls Y\ls P\ls E\\
        Electronic Products and Composition Group,\\
        Printing Division, Cambridge University Press,
        CB2 2BS.}

\received{20 March 1995; revised 30 September 1998}

\pagerange{\pageref{firstpage}--\pageref{lastpage}}
\pubyear{1998}

\newcommand\eg{{\it e.g.\ }}
\newcommand\etc{{\it etc}}

\begin{document}

\label{firstpage}
\maketitle

\begin{abstract}
This guide is for authors who are preparing papers for the {\em Natural
Language Engineering\/} journal using the \LaTeX\ document preparation
system and the CUP NLE style file.
\end{abstract}

\section{Introduction}

\section{Introduction}

The layout design for the {\em Natural Language Engineering\/} journal
has been implemented as a \LaTeX\ style file. The NLE style file is based
on the ARTICLE style as discussed in the \LaTeX\ manual. Commands which
differ from the standard \LaTeX\ interface, or which are provided in addition
to the standard interface, are explained in this guide. This guide is not a
substitute for the \LaTeX\ manual itself.

\begin{tabular}{ |p{3cm}|p{3cm}|p{3cm}|  }
\hline
\multicolumn{3}{|c|}{Country List} \\
\hline
Country Name     or Area Name& ISO ALPHA 2 Code &ISO ALPHA 3 \\
\hline
Afghanistan & AF &AFG \\
Aland Islands & AX   & ALA \\
Albania &AL & ALB \\
Algeria    &DZ & DZA \\
American Samoa & AS & ASM \\
Andorra & AD & AND   \\
Angola & AO & AGO \\
\hline
\end{tabular}

\label{lastpage}

\end{document}

Answer 1

Unfortunately, the class defines some tabular-like environments for the author part using low level commands that depend on the kernel tabular, which are overwritten by array. This is a bad error on their part, because this makes the class incompatible with a standard package.

However, not all is lost, because we can redefine the nle tabular-like commands before loading pgfplotstable, so avoiding the incompatibility.

\documentclass{nle}

\makeatletter
\let\O@argtabularcr\@argtabularcr
\def\O@xtabularcr{\@ifnextchar[\O@argtabularcr{\ifnum 0=`{\fi}\cr}}
\let\O@tabacol\@tabacol
\let\O@tabclassiv\@tabclassiv
\let\O@tabclassz\@tabclassz
\let\O@tabarray\@tabarray
\def\author@tabular{\authorsize\def\@halignto{}\@authortable}
\let\endauthor@tabular=\endtabular
\def\author@tabcrone{{\ifnum0=`}\fi\O@xtabularcr\affilsize\itshape
 \let\\=\author@tabcrtwo\ignorespaces}
\def\author@tabcrtwo{{\ifnum0=`}\fi\O@xtabularcr[-3\p@]\affilsize\itshape
 \let\\=\author@tabcrtwo\ignorespaces}
\def\@authortable{\leavevmode \hbox \bgroup $\let\@acol\O@tabacol
 \let\@classz\O@tabclassz \let\@classiv\O@tabclassiv
 \let\\=\author@tabcrone \ignorespaces \O@tabarray}
\makeatother

\usepackage{pgfplotstable} 


\title[Natural Language Engineering]
      {Natural Language Engineering \LaTeX\ Supplement}
\author[\LaTeX\ Supplement]
       {C\ls A\ls M\ls B\ls R\ls I\ls D\ls G\ls E\ns
        \TeX\ls -\ls T\ls O\ls -\ls T\ls Y\ls P\ls E\\
        Electronic Products and Composition Group,\\
        Printing Division, Cambridge University Press,
        CB2 2BS.}

\received{20 March 1995; revised 30 September 1998}

\pagerange{\pageref{firstpage}--\pageref{lastpage}}
\pubyear{1998}

\newcommand\eg{{\it e.g.\ }}
\newcommand\etc{{\it etc}}

\begin{document}

\label{firstpage}
\maketitle

\begin{abstract}
This guide is for authors who are preparing papers for the {\em Natural
Language Engineering\/} journal using the \LaTeX\ document preparation
system and the CUP NLE style file.
\end{abstract}

\section{Introduction}

\section{Introduction}

The layout design for the {\em Natural Language Engineering\/} journal
has been implemented as a \LaTeX\ style file. The NLE style file is based
on the ARTICLE style as discussed in the \LaTeX\ manual. Commands which
differ from the standard \LaTeX\ interface, or which are provided in addition
to the standard interface, are explained in this guide. This guide is not a
substitute for the \LaTeX\ manual itself.

\label{lastpage}

\end{document}