% folarrow-lite-en.tex: the manual of the light version (lite option) of the folarrow package (English)
% Compile: uplatex folarrow-lite-en && uplatex folarrow-lite-en && dvipdfmx folarrow-lite-en
% (upLaTeX, because the source of the Japanese example contains Japanese text)
% The outputs of the examples (lite-examples/ex*-out.pdf) were made by compiling the sources of the examples.
\documentclass[dvipdfmx,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{textcomp}
\usepackage{upquote}
\usepackage[margin=25mm]{geometry}
\usepackage{graphicx}
\usepackage{array}
\usepackage{fancyvrb}
\usepackage{url}
\title{The folarrow package, light version\\\large Manual of the \texttt{lite} option}
\author{Yuwsuke Kieda}
\date{2026-10-10\quad v20261010.0}
\newcommand\pkg[1]{\textsf{#1}}
\newcommand\file[1]{\texttt{#1}}
\fvset{frame=single,framesep=3mm,fontsize=\small}
\setlength\emergencystretch{3em}
% An example: the source (the file as it is) and the result
% (the command, source and result are kept in one box, not broken across pages or separated from the heading)
\newcommand\example[2]{%
  \par\noindent\begin{minipage}{\linewidth}
  Compile: \texttt{#2}\par
  \VerbatimInput{lite-examples/#1.tex}%
  \par\noindent Result:\par
  \begin{center}\fbox{\includegraphics{lite-examples/#1-out.pdf}}\end{center}
  \end{minipage}\par\medskip}
\begin{document}
\maketitle

\noindent A Japanese version of this manual is \file{folarrow-lite-ja.pdf}.

\section{Overview}

\pkg{folarrow} is a package that makes arrows with three slanted strokes on the shaft, which
denote the projection of a foliated bundle, available in \pkg{amscd}, \pkg{xy-pic} and
\pkg{tikz-cd} diagrams and in inline math. This manual describes its light version (the
\texttt{lite} option).
\begin{Verbatim}
\usepackage[lite]{folarrow}
\end{Verbatim}
The light version uses no file other than \file{folarrow.sty} (no Lua module, measured data or
arrow fonts) and draws every arrow as the usual arrow of each package with three slanted strokes
drawn over it. Use it, for example, when you do not want the arrow fonts embedded in the PDF.

\section{Preparation}

\begin{itemize}
\item Install the \pkg{folarrow} package (if your \TeX{} distribution includes it, it can be used
  as it is).
\item \LaTeX{} 2022-06-01 or later is required. The package loads \pkg{pict2e} and \pkg{graphics}
  (both are in \TeX{} Live). For diagrams, load the ones of \pkg{amscd}, \pkg{xy-pic} and
  \pkg{tikz-cd} that you use.
\item It works with pdf\LaTeX, Lua\LaTeX, Xe\LaTeX{} and up\LaTeX{}+dvipdfmx. With up\LaTeX, give
  the \texttt{dvipdfmx} option to the document class.
\end{itemize}

\section{Loading}

\begin{Verbatim}
\usepackage{amscd}        % only the ones you use
\usepackage[all]{xy}
\usepackage{tikz-cd}
\usepackage[lite]{folarrow}
\end{Verbatim}
\pkg{amscd}, \pkg{xy-pic} and \pkg{tikz-cd} may be loaded before or after \pkg{folarrow}.
\texttt{lite} can only be given when loading the package (it cannot be changed later with
\verb|\folarrowsetup|). The shape keys of the strokes (section~\ref{sec:shape}) may be given
together with \texttt{lite}.
\begin{Verbatim}
\usepackage[lite, gap=0.45]{folarrow}
\end{Verbatim}

\section{Commands}

\subsection{amscd}
Add \verb|F| right after the \verb|@| of the usual arrows \verb|@>>>|, \verb|@<<<|, \verb|@VVV|
and \verb|@AAA| to get the strokes. Labels are given in the same way as for the usual arrows.
\begin{center}
\begin{tabular}{ll}
\verb|@F>>>|, \verb|@F<<<| & horizontal (right, left)\\
\verb|@FVVV|, \verb|@FAAA| & vertical (down, up)
\end{tabular}
\end{center}

\subsection{xy-pic}
Place the object \verb|fol| on an arrow with \verb/|/, as in \verb/\ar[d]|@{fol}/. The arrow is
not broken, and it also works on diagonal arrows. Enclose a label of the arrow in \verb|\folpad|
to give it a margin that clears the strokes.
\begin{Verbatim}
\ar[d]|@{fol}^{\folpad{\pi}}
\end{Verbatim}

\subsection{tikz-cd}
Add \verb|foliated| to the options of the arrow. Labels clear the strokes automatically.
\begin{Verbatim}
\arrow[d, foliated, "\pi"]
\end{Verbatim}

\subsection{Inline math}
\begin{center}
\begin{tabular}{ll}
\verb|\folrightarrow| & right arrow (\verb|\longrightarrow| with the strokes)\\
\verb|\folleftarrow| & left arrow (\verb|\longleftarrow| with the strokes)\\
\verb|\foldownarrow|, \verb|\foluparrow| & down arrow, up arrow\\
\verb|\xfolrightarrow[below]{above}| & right arrow that stretches with the labels\\
\verb|\xfolleftarrow[below]{above}| & left arrow that stretches with the labels
\end{tabular}
\end{center}
All of them are relations (\verb|\mathrel|) and can be used in subscripts. The stretchable arrows
are used like \verb|\xrightarrow| of \pkg{amsmath} and are never shorter than
\verb|\longrightarrow|.

\section{Adjusting the strokes}\label{sec:shape}

Use package options or \verb|\folarrowsetup|. \verb|\folarrowsetup| inside a group affects only
that group.
\begin{center}\small
\begin{tabular}{lll}
Key & Default & Meaning\\\hline
\verb|span| & 1.0 & length of the strokes (ratio to the arrowhead width; $>0$, $\le 10$)\\
\verb|lean| & 0.25 & slant (offset along the arrow relative to the length; $-5$ to 5)\\
\verb|gap| & 0.35 & spacing of the strokes (ratio to the arrowhead width; 0 to 10)\\
\verb|shift| & 0 & shift from the middle toward the tail (ratio to the arrowhead width; $-10$ to 10)\\
\verb|thickness| & (empty) & line thickness; if empty, the shaft thickness (estimated)
\end{tabular}
\end{center}

\section{Examples}

Each example can be compiled by copying it, from \verb|\documentclass| to \verb|\end{document}|,
into a file. The results were actually typeset (with the margins cropped). To make sure that no
other files are used, they were compiled with no file of \pkg{folarrow} other than
\file{folarrow.sty} available.

\subsection{amscd}
\example{ex01-amscd}{pdflatex ex01-amscd}

\subsection{xy-pic}
\example{ex02-xypic}{pdflatex ex02-xypic}
In \TeX{} Live 2025 and 2026, \pkg{xy-pic} itself fails with Lua\LaTeX{} (unrelated to
\pkg{folarrow}). Use \pkg{xy-pic} with pdf\LaTeX{} or up\LaTeX.

\subsection{tikz-cd}
\example{ex03-tikzcd}{pdflatex ex03-tikzcd}

\subsection{Inline math}
\example{ex04-inline}{pdflatex ex04-inline}

\subsection{Adjusting the strokes}
\example{ex05-setup-en}{pdflatex ex05-setup-en}
\verb|\folarrowsetup{gap=0.45}| in the preamble affects the whole document. \verb|\folarrowsetup|
used inside a group (\verb|{| and \verb|}|) affects only that group, and the setting of the whole
document is restored after the group. The diagrams are, from left to right: the setting of the
whole document (\verb|gap=0.45|); in addition \verb|span=1.5, lean=0.5|;
\verb|thickness=0.8pt| (\pkg{tikz-cd}); back to the setting of the whole document. The inline
arrows are, from left to right: the setting of the whole document; in addition \verb|shift=0.5|
(the strokes are moved toward the tail of the arrow); back to the setting of the whole document.

\subsection{Times (newtx)}
\example{ex06-times}{pdflatex ex06-times}

\subsection{Palatino (newpx)}
\example{ex07-palatino}{pdflatex ex07-palatino}

\subsection{A Japanese document (up\LaTeX{}+dvipdfmx)}
\example{ex08-uplatex}{uplatex ex08-uplatex \&\& dvipdfmx ex08-uplatex}

\subsection{Lua\LaTeX{} and unicode-math}
\example{ex09-lualatex}{lualatex ex09-lualatex}

\subsection{Xe\LaTeX{} and unicode-math}
\example{ex10-xelatex}{xelatex ex10-xelatex}

\section{Properties and limitations of the light version}

\begin{itemize}
\item The width of the arrowhead and the line thickness (the reference for the size of the
  strokes) are read from the glyph bounding box with Xe\LaTeX{} and an OpenType math font (using
  \verb|\XeTeXglyphbounds|), and estimated from the font dimensions otherwise.
\item The strokes are placed at the center of the arrow's box. This may differ from the center of
  the arrow's ink (the part actually painted): for the inline arrows of 10\,pt Computer Modern,
  \pkg{newtxmath}, \pkg{newpxmath} and \pkg{txfonts}, the offset was up to 0.3\,pt along the arrow
  and 0.03\,pt across it. With some fonts it is larger.
\item The ends of the strokes are always butt.
\item In bold, with \verb|\boldmath| etc., the length and thickness of the strokes are also
  estimated from the font dimensions, so the strokes may be somewhat thin for the bold arrows.
\item The result is an arrow with three strokes drawn over it, so copying it from the PDF gives
  the original arrow character (for \verb|\foldownarrow|, the pieces of the delimiter).
\item With Lua\LaTeX, the extensible $\uparrow$ of Luciole Math gives the error
  ``\texttt{Extensible recipe has no fixed parts}'' (a problem of the font; it happens without
  \pkg{folarrow} too). In the light version, \verb|\foluparrow| and \verb|@FAAA| of \pkg{amscd}
  give this error.
\item In Pennstander Math, the large delimiters $\downarrow$ and $\uparrow$ are broken (a problem
  of the font). In the light version this shows as it is in \verb|\foldownarrow|,
  \verb|\foluparrow| and the vertical arrows of \pkg{amscd}.
\item With Xe\LaTeX, OpenType fonts included in \TeX{} Live may not be found by their names.
  Specify them by file name, as follows.
\begin{Verbatim}
\setmathfont{latinmodern-math.otf}
\end{Verbatim}
\end{itemize}

\section{Notes}

\begin{itemize}
\item A key value that is not a number or is out of range (see the table of
  section~\ref{sec:shape}) gives an error showing the name and value of the key, and the previous
  value is kept.
\item The commands can be used in the arguments of \verb|\section|, \verb|\caption|, etc. In
  \pkg{hyperref} bookmarks, the arrows become the characters
  $\rightarrow\leftarrow\downarrow\uparrow$.
\item \pkg{amscd}, \pkg{xy-pic}, \pkg{tikz-cd} and \pkg{unicode-math} may be loaded before or
  after \pkg{folarrow}.
\item In vertical writing with p\TeX/up\TeX{} and dvipdfmx, too, the strokes are rotated for
  vertical writing. To typeset diagrams in vertical writing, put them in a horizontal box such as
  \verb|\hbox{\yoko ...}|.
\item With babel's spanish, \pkg{amscd} itself cannot be used (this happens without
  \pkg{folarrow} too). Use the \verb|es-noquoting| option or \verb|\deactivatequoting|.
\item For colored arrows of \pkg{xy-pic}, give the color to the strokes too:
  \verb/\ar@[red][r]|*[red]\dir{fol}/.
\item At large sizes, load \pkg{amsmath} or exscale (so that the vertical arrows do not stay
  small).
\end{itemize}

\section{Differences from the full version}

The full version, without \texttt{lite}, uses the following files besides \file{folarrow.sty}
for more accurate results.
\begin{center}
{\renewcommand\arraystretch{1.3}%
\begin{tabular}{>{\raggedright\arraybackslash}p{.25\linewidth}%
  >{\raggedright\arraybackslash}p{.38\linewidth}>{\raggedright\arraybackslash}p{.27\linewidth}}
 & Full version & Light version (\texttt{lite})\\\hline
Files needed & \file{folarrow.sty}, \file{folarrow.lua}, tables of the measured data and the
  arrow fonts (\file{.def}), the arrow fonts (Type~1, OTF) and the map file & \file{folarrow.sty} only\\
Inline arrows & a single glyph of a font with the strokes (major fonts) & the strokes drawn over
  the arrow\\
Value as text & $\rightarrow\leftarrow\downarrow\uparrow$ & the original arrow characters\\
Arrowhead width and line thickness & measured data, glyph shapes (Lua\LaTeX, Xe\LaTeX) &
  estimated (glyph shapes with Xe\LaTeX)\\
Offset of the strokes from the center & at most 0.015\,pt (inline arrows) & up to about 0.3\,pt\\
Ends of the strokes & round or butt, following the tail of the arrow & always butt
\end{tabular}}
\end{center}
The usage of the full version and the results of the verification are in the manual
\file{folarrow-en.pdf}.

\section{License and author}

\file{folarrow.sty}, \file{folarrow.lua}, the \file{.def} files, the documentation and the tools
are distributed under the MIT License (\file{LICENSE}). The arrow fonts (\file{fonts/}) were made
from other fonts and keep the licenses of their original fonts (SIL Open Font License 1.1, GUST
Font License, GNU GPL with font exception). The original font, original copyright notice and
license of each font are listed in \file{licenses/FONTS.md}, and the license texts are in
\file{licenses/}.

Author: Yuwsuke Kieda

\end{document}