Vertical spacing between paragraphs in elsarticle.cls

Question

Would I be defying elsarticle.cls if I wanted to have a little vertical spacing between paragraphs?

If not, why doesn't placing \setlength{\parsep}{12pt} in the calling document preamble work?

Here is how \parsep is set in elsarticle.cls.

 \setlength{\parsep}{0pt plus1pt minus1pt}%
 \setlength{\parskip}{0pt plus1pt minus1pt}

Here is an mwe which allows exploration of this:

\documentclass[review]{elsarticle}
\usepackage{lineno}
\usepackage{lipsum}

\setlength{\parindent}{12pt} % this works
\setlength{\parsep}{12pt} % this not having an effect

% set frequency of line numbers
\modulolinenumbers[2]

\journal{The Periodical}

% `Elsevier LaTeX' style
\bibliographystyle{plainnat}

\begin{document}

\begin{frontmatter}
% include title and subtitle
\title{The title}
% include authors, addresses, corresponding author
\author{Author}
\begin{abstract}
\end{abstract}
\begin{keyword}
easy, should-know-this, trivial, annoying, probably need help with the plus minus representation of lengths thing, apologies in advance
\end{keyword}
\end{frontmatter}

% select to show line numbers
\linenumbers

\tableofcontents

\newpage


% introduction
\section{Introduction}

\lipsum[2]\\

\lipsum[3-4]

\end{document}

Answer 1

I think that you should have changed \parskip, instead of \parsep.

If you are submitting to a publication that uses the elsarticle class it is best not to change the layout of the printed work, but if it is for some other use then go ahead and see if you get any complaints.