\NeedsTeXFormat{LaTeX2e}
\ProvidesClass{iac_class}[2021/09/01 International Astronautical Congress conference paper LaTeX class]

\LoadClass[twocolumn,letter paper,10pt]{article}
\setlength\parskip{0pt} % no spacing at double return carriage

%-----------------------------------------------------
%% ------------ PACKAGES -----------------------------
%\RequirePackage{amsmath}
%\RequirePackage{amssymb}
%\RequirePackage{amstext}
%\RequirePackage{amsfonts}
\RequirePackage{graphicx}
%\RequirePackage{array}
\RequirePackage{booktabs}
\RequirePackage{cite}
\RequirePackage{lastpage}
\RequirePackage{fancyhdr}
\RequirePackage[explicit,compact]{titlesec}
\RequirePackage[normalem]{ulem}
\RequirePackage{etoolbox}
\RequirePackage{alphalph}
\RequirePackage{float}

\renewcommand{\headrulewidth}{0pt}

%-----------------------------------------------------
%% ------------ APPEARANCE ---------------------------
% Document setup
\RequirePackage[margin=2.25cm,top=3.35cm,bottom=3.35cm,headheight=\baselineskip]{geometry} % page layout
\setlength{\columnsep}{0.8cm} % column spacing
% Set Times New Roman
\usepackage[T1]{fontenc}
\usepackage{newtxmath,newtxtext}

% Captions
\RequirePackage[]{caption}
\captionsetup[figure]{name=Fig.,format=hang,indention=-20pt}
%\captionsetup[table]{format=hang,indention=-24pt}

% Sections spacing
\titlespacing{\section}{0pt}{15pt}{1pt}
\titlespacing{\subsection}{0pt}{15pt}{1pt}
\titlespacing{\subsubsection}{0pt}{15pt}{1pt}

% Sections style
\titleformat{\section}{\bfseries}{\arabic{section}. }{0.5em}{{#1}} % Davide: modified syle & numbering  
\titleformat{\subsection}{\itshape}{\arabic{section}.\arabic{subsection}}{0.5em}{{#1}} % Davide: modified syle & numbering
\titleformat{\subsubsection}{\itshape}{\arabic{section}.\arabic{subsection}.\arabic{subsubsection}}{0.5em}{{#1}} % Davide: modified syle & numbering

%-----------------------------------------------------
%% ------------ IAC CUSTOM PART ----------------------
\newcounter{authcount}
\newcommand{\IACauthor}[3]{%
	\stepcounter{authcount}%
	\csdef{iac@author\theauthcount}{#1}%
	\csdef{iac@affiliation\theauthcount}{#2}%
	\csdef{iac@iscorrespondingauthor\theauthcount}{#3}}%
%

\renewcommand{\abstract}[1]{\def\iac@abstract{#1}}
\newcommand*{\IACpaperyear}[1]{\def\iac@paperyear{#1}}\IACpaperyear{}
\newcommand*{\IACpapernumber}[1]{\def\iac@papernumber{#1}}\IACpapernumber{}
\newcommand*{\IACconference}[1]{\def\iac@conference{#1}}\IACconference{}
\newcommand*{\IACcopyright}[1]{\def\iac@copyright{#1}}\IACcopyright{}
\newcommand*{\IAClocation}[1]{\def\iac@location{#1}}\IAClocation{}
\newcommand*{\IACdate}[1]{\def\iac@date{#1}}\IACdate{}

\newcommand{\IACcopyrightA}[1]{\def\iac@copyright{Copyright \copyright\ \iac@paperyear\ by the International Astronautical Federation. All rights reserved.}}
\newcommand{\IACcopyrightB}[1]{\def\iac@copyright{Copyright \copyright\ \iac@paperyear\ by #1. Published by the IAF, with permission and released to the IAF to publish in all forms.}}
\newcommand{\IACcopyrightC}[1]{\def\iac@copyright{#1}} 
\newcommand\iac@makecopyright{{\iac@copyright}}

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  \newpage
  \begin{center}%
    \iac@papernumber\par%
    \vskip1em
    {\large \textbf{{\@title}} \par}%
    \vskip 1.5em%
    {\large
      \lineskip .5em%
      \newcounter{authnum}%
      \setcounter{authnum}{0}
      \whileboolexpr
      { test {\ifnumcomp{\value{authnum}}{<}{\theauthcount}} }%
        {\stepcounter{authnum}%
      	\normalsize\textbf{\csuse{iac@author\theauthnum}}\textsuperscript{\@alph{\theauthnum}}%
      	{\ifnumcomp{\csuse{iac@iscorrespondingauthor\theauthnum}}{=}{1}{*}{}}%
      	{\ifnumcomp{\value{authnum}}{=}{\theauthcount}{}{,\ }}%\par%
		%\normalsize\csuse{iac@affiliation\theauthnum}\par%
		%\vskip 1.5ex%
	    }%
    }%
  \end{center}%
    \setcounter{authnum}{0}
    \whileboolexpr
      { test {\ifnumcomp{\value{authnum}}{<}{\theauthcount}} }%
      {\stepcounter{authnum}%
		\textsuperscript{\@alph{\theauthnum}} \normalsize\textit{\csuse{iac@affiliation\theauthnum}}\par%
		\vskip 1.5ex%
	  }
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    \whileboolexpr
      { test {\ifnumcomp{\value{authnum}}{<}{\theauthcount}} }%
      {\stepcounter{authnum}%
		\ifnumcomp{\csuse{iac@iscorrespondingauthor\theauthnum}}{=}{1}{* Corresponding author}{}\par%
		%\vskip 1.5ex%
	  }
%
  \begin{center}
      \textbf{Abstract}
  \end{center}
  \indent\iac@abstract\par%
  \vskip 4.5ex%
  }%

% Set header and footer
\pagestyle{fancy}%
\fancyhf{}

% Header
\chead{\footnotesize International Astronautical Congress, {\iac@location}, {\iac@date}.\\ \iac@makecopyright}

% Footer
\setlength{\footskip}{40pt}
\rfoot{Page \thepage\ of \pageref{LastPage}}
\lfoot{\iac@papernumber}