Add "This version" and "First version" in abstract

Question

I am trying to add on separate lines "This version" and "First version". I have tried the following code, but it does not seem to work:

\renewcommand*{\today}{\normalsize{This draft: December 2018}} 
\renewcommand*{\newline}{\normalsize{First draft: March 2015}} 

Any help will be greatly appreciated.

The ideal outcome would look like as follows:

Answer 1

At first you need to define two commands in the preamble \thisdraft and \firstdraft which you are supposed to use later in your document. These commands includes the words of your choice (in your case "This draft: December 2018" and "First draft: March 2015"). Then place the commands as an arguments in the date{} commands of the article so that you ensure the commands output will be printed in the place designated for the date{} in the article title. The code will be as follows:

\documentclass{article}
%
%
\newcommand*{\thisdraft}{This draft: December 2018} % define command
\newcommand*{\firstdraft}{First draft: March 2015}  % define command
%
\title{Title}
\author{Name}
%
\date{\thisdraft \\ \firstdraft}

\begin{document}

\maketitle

\hrule % optional rule after title

\begin{abstract}
Type your abstract here.
\end{abstract}

\section{Sec One}

\end{document}

The output will be:

You can later change the arguments of the commands \thisdraft and \firstdraft according to your needs.

Answer 2

Why redefine such important commands? The commands \today and \newline that you are trying to re-define are mainly used in latex in many classes and packages definitions. Re-defining them may cause unnecessary issues.

You can use \newcommand*{\mytoday} and \newcommand*{\mynewline} instead a follows.

\newcommand*{\mytoday}{\normalsize{This draft: December 2018}} 
\newcommand*{\mynewline}{\normalsize{First draft: March 2015}} 

and then use them in the text as \mytoday{} and \mynewline{}.

I would also suggest choosing a better command name (e.g. \mytoday --> \myversion and \mynewline --> \myfirstversion).