\documentclass[twoside,10pt]{book}
+\def\mytitle{Big Things for Tiny Computers}
+\def\mysubtitle{Task Oriented Programming for the Internet of Things}
+\def\myauthor{Mart Lubbers}
+
\input{preamble}
% Just for the blind text, can go when it's finished
}
% Document info
-\title{Some title}
-\author{Some author}
+\title{\mytitle{} --- \mysubtitle{}}
+\author{Mart Lubbers}
\date{\formatdate{1}{6}{2023}}
\input{an_appendix}
\backmatter%
-\stopthumb% chktex 9
\addtitlethumb{Backmatter}{}{white}{gray}{pagesLTS.0}
% Bibliography
\label{chp:index}
\printindex
-\end{document} % chktex 10
+\end{document}