How do I apply appendix-only page-numbering: A1 (first page, first appendix), B6 (page six, app B)?

Question

I am trying to get my appendices to be page-numbered with the letter of their chapter and then the page we are at relative to how far into the particular appendix. For instance the third page of the first appendix would be numbered A3, the first of appendix B B1 and the eleventh of appendix Q Q11.

\documentclass{book}
\usepackage[top=2cm, bottom=3cm, left=3.5cm, right=3.5cm, a4paper]{geometry} %margins
\usepackage{setspace}
\onehalfspacing % 1.15 line distance
\setlength{\parskip}{8pt} % 8pt paragraph distance
\setlength{\parindent}{0pt} % Remove the indentation from the beginning of the paragraphs
\usepackage{fontspec} % compile w/XeLaTeX
\setmainfont{Perpetua}
\usepackage[style=apa, backend=biber, useprefix=false]{biblatex}
\AtEveryCitekey{\toggletrue{blx@useprefix}}
\setlength\bibitemsep{\baselineskip}
\bibliography{main.bib}
\addbibresource{main.bib}
\usepackage{titlesec} % for customising chapter titles
\newfontfamily\verdana{Verdana}
\usepackage{xcolor} 
\usepackage[xindy,toc,nopostdot]{glossaries} %numberedsection=nameref,
\makeglossaries % Make LaTeX produce the files required to compile the glossary
\makeatletter % https://tex.stackexchange.com/questions/18604/chapter-formatting
\def@makechapterhead#1{%
  {\parindent \z@ \raggedright \verdana\fontsize{14pt}{0pt}\bfseries
    \ifnum \c@secnumdepth >\m@ne
        \thechapter.\ % <-- Chapter # (without "Chapter")
    \fi
    \interlinepenalty@M
    #1\par\nobreak% <------------------ Chapter title
    \vskip 12pt% <------------------ Space between chapter title and first paragraph
  }}
\makeatother
\titleformat{\section} % specifies the format for the section headings
{\fontsize{12pt}{14.4pt}\selectfont\verdana\bfseries} % font size and family to Verdana 12pt
{\thesection}{1em}{} % {spacing between the section number and the title, which is set to 1em}{format for the section title, left blank}
\titlespacing{\section}{0pt}{18pt}{6pt}
\titleformat{\subsection}
{\fontsize{13pt}{15.6pt}\selectfont\bfseries\fontspec{Perpetua}}{\thesubsection}{1em}{}
\titlespacing{\section}{0pt}{12pt}{6pt}
\titleformat{\subsubsection}
{\fontsize{12pt}{14.4pt}\selectfont\fontspec{Perpetua}}{\thesubsubsection}{1em}{\underline}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{} % clear all header and footer fields
\renewcommand{\headrule}{} % Remove the horizontal line from the header
\fancyfoot[C]{\fontfamily{ppl}\fontsize{11}{13}\selectfont\thepage} % set the footer centred and using Perpetua 11 font
\usepackage{etoolbox} % for patching \appendix
\makeatletter
\patchcmd{\appendix}{@mainsect}{@appendixsect}{}{}
\patchcmd{@chapter}{\global@topnum}{\global@topnum\m@ne}{}{}
\makeatother
\newcommand{\specialpage}{%
  \newpage%
  \begingroup%
  \pagenumbering{gobble}% change to gobble page numbering style
  %\renewcommand{\headrulewidth}{0pt}%
  \vspace{-2cm}%
  \centerline{\textcolor[HTML]{676767}{\fontsize{11pt}{13.2pt}\selectfont \textit{This page is special}}}%
  \vspace{\fill}%
  \thispagestyle{empty}% remove page number
  \endgroup%
  \clearpage%
  \pagenumbering{roman}% switch back to a normal page numbering style
}
\begin{document}
\fontsize{13pt}{15.6pt}\selectfont
\frontmatter
    \pagenumbering{roman} % Change page numbering to lowercase Roman numerals
    \specialpage
    \newpage % Continue with your main document
    \input{chapters/preface.tex}
    \input{chapters/abstract.tex}
    % There needs to be an empty page here.
    \tableofcontents
    \listoffigures
    \listoftables
    \lstlistoflistings
    \input{glossary.tex} % Include the glossary definitions
\mainmatter
    \pagenumbering{arabic}
    \setcounter{page}{1} % Reset page counter to 1
    \input{chapters/1. introduction.tex}
    \newpage
    \printbibliography
\appendix
    % Redefine the header and footer for the appendix
    %\fancyhead{} % clear all header fields
    %\fancyfoot[C]{\fontfamily{ppl}\fontsize{11}{13}\selectfont\thepage} % set the footer centred and using Perpetua 11 font
    \renewcommand{\thechapter}{\Alph{chapter}}
    \setcounter{chapter}{0}
    \input{chapters/app - people.tex}
    \input{chapters/app - design.tex}
\end{document}

Any thoughts?

Answer 1

I'll remove all of the unnecessary parts, concentrating on the actual issue.

But, please, remove \pagenumbering{roman} after \frontmatter and \pagenumbering{arabic}\setcounter{page}{1} after \mainmatter, because the corresponding instructions are already performed.

\documentclass{book}
\usepackage[a5paper]{geometry} % just for smaller pages
\usepackage{kantlipsum} % for filler text
\newcommand{\appendixchapter}{%
  \cleardoublepage
  \setcounter{page}{1}%
  \renewcommand{\thepage}{\thechapter\arabic{page}}%
  \chapter
}
\begin{document}
\frontmatter
\tableofcontents
\mainmatter
\chapter{First}
\kant
\appendix
\appendixchapter{First appendix}
\kant
\appendixchapter{Second appendix}
\kant
\appendixchapter{Third appendix}
\kant
\end{document}

Instead of a \fontsize declaration, if you really want 13pt size, do

\usepackage[fontsize=13pt]{fontsize}

A slightly different approach, that doesn't require a special command for appendices.

\documentclass{book}
\usepackage[a5paper]{geometry} % just for smaller pages
\usepackage{kantlipsum} % for filler text
\newcommand{\doappendixchapter}{%
  \cleardoublepage
  \setcounter{page}{1}%
  \renewcommand{\thepage}{\thechapter\arabic{page}}%
}
\AddToHook{cmd/appendix/after}{%
  \AddToHook{cmd/chapter/before}{\doappendixchapter}%
}
\begin{document}
\frontmatter
\tableofcontents
\mainmatter
\chapter{First}
\kant
\appendix
\chapter{First appendix}
\kant
\chapter{Second appendix}
\kant
\chapter{Third appendix}
\kant
\end{document}